U.S. patent number 11,118,004 [Application Number 16/095,384] was granted by the patent office on 2021-09-14 for three-dimensional inkjet printing using ring-opening metathesis polymerization.
This patent grant is currently assigned to Stratasys Ltd.. The grantee listed for this patent is Stratasys Ltd.. Invention is credited to Renata Drozdzak-Matusiak, Lev Kuno, Asher Razlan, Gilles Recher, Yuval Vidavsky, Ira Yudovin-Farber.
United States Patent |
11,118,004 |
Vidavsky , et al. |
September 14, 2021 |
Three-dimensional inkjet printing using ring-opening metathesis
polymerization
Abstract
Methods for fabricating three-dimensional objects by 3D-inkjet
printing technology are provided. The methods utilize curable
materials that polymerize via ring-opening metathesis
polymerization (ROMP) for fabricating the object, in combination
with acid-activatable pre-catalyst and an acid generator activator.
Kits containing modeling material formulations usable in the
methods are also provided.
Inventors: |
Vidavsky; Yuval (Moshav
Sitriya, IL), Yudovin-Farber; Ira (Rehovot,
IL), Razlan; Asher (Rehovot, IL), Kuno;
Lev (Tzur-Hadassah, IL), Recher; Gilles (Marcq en
Baroeul, FR), Drozdzak-Matusiak; Renata (Wasquehal,
FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Stratasys Ltd. |
Rehovot |
N/A |
IL |
|
|
Assignee: |
Stratasys Ltd. (Rehovot,
IL)
|
Family
ID: |
1000005804502 |
Appl.
No.: |
16/095,384 |
Filed: |
February 5, 2017 |
PCT
Filed: |
February 05, 2017 |
PCT No.: |
PCT/IL2017/050141 |
371(c)(1),(2),(4) Date: |
October 22, 2018 |
PCT
Pub. No.: |
WO2017/187434 |
PCT
Pub. Date: |
November 02, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190127517 A1 |
May 2, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62327525 |
Apr 26, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y
70/00 (20141201); B29C 64/112 (20170801); B33Y
10/00 (20141201); C08G 61/08 (20130101); C08G
2261/418 (20130101) |
Current International
Class: |
C08G
61/08 (20060101); B33Y 70/00 (20200101); B29C
64/112 (20170101); B33Y 10/00 (20150101) |
References Cited
[Referenced By]
U.S. Patent Documents
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103338864 |
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Oct 2013 |
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1498256 |
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EP |
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1757613 |
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Feb 2007 |
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EP |
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2280017 |
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Feb 2011 |
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EP |
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2452958 |
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May 2012 |
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EP |
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2460587 |
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Jun 2012 |
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EP |
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2480587 |
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Aug 2012 |
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EP |
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2801588 |
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Nov 2014 |
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EP |
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2382798 |
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Jun 2003 |
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GB |
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Sep 2002 |
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JP |
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Sep 2005 |
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JP |
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2010-095706 |
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Apr 2010 |
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JP |
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2010-214858 |
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Sep 2010 |
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JP |
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2014-506260 |
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Mar 2014 |
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JP |
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WO 97/20865 |
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Jun 1997 |
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WO |
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WO 97/29135 |
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WO |
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WO 99/51344 |
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WO 2013/128452 |
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Sep 2013 |
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WO 2014/144634 |
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Sep 2014 |
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WO 2016/063282 |
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WO 2016/125170 |
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WO |
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WO 2017/134676 |
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Aug 2017 |
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WO |
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WO 2017/187434 |
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Nov 2017 |
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WO |
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Primary Examiner: Sastri; Satya B
Parent Case Text
RELATED APPLICATIONS
This application is a National Phase of PCT Patent Application No.
PCT/IL2017/050141 having International filing date of Feb. 5, 2017,
which claims the benefit of priority under 35 USC .sctn. 119(e) of
U.S. Provisional Patent Application No. 62/327,525 filed on Apr.
26, 2016. The contents of the above applications are all
incorporated by reference as if fully set forth herein in their
entirety.
Claims
What is claimed is:
1. A method of fabricating a three-dimensional object, the method
comprising sequentially forming a plurality of layers in a
configured pattern corresponding to the shape of the object,
thereby fabricating the object, wherein said formation of each
layer comprises dispensing at least two modeling material
formulations by at least two inkjet printing heads, each head
jetting one of said at least two modeling material formulations,
said at least two modeling material formulations comprising an
unsaturated cyclic monomer polymerizable by ring opening metathesis
polymerization (ROMP) and a catalyst system for initiating ROMP of
said monomer, said catalyst system comprising a pre-catalyst and an
activator for chemically activating said catalyst towards
initiating ROMP of said monomer, wherein at least one of said
modeling material formulations comprises said pre-catalyst and at
least another modeling material formulation comprises said
activator and is devoid of said pre-catalyst, wherein said
pre-catalyst is an acid-activatable ruthenium-based pre-catalyst
and said activator is active towards chemically activating said
pre-catalyst, wherein said pre-catalyst comprises at least two
pre-catalysts, wherein one of said pre-catalysts is ##STR00068##
and another one of said pre-catalysts is ##STR00069##
2. The method of claim 1, wherein said activator is represented by
Formula: (R).sub.nSi(Cl).sub.4-n wherein: n is 1, 2, or 3, and R is
selected from hydrogen, alkyl and aryl, such that when n is 2 or 3,
each R can be the same or different, wherein at least one R is
selected from alkyl and aryl.
3. The method of claim 1, wherein at least one of said modeling
material formulations further comprises a toughening agent.
4. The method of claim 1, wherein a temperature of an inkjet
printing head for dispensing said at least one modeling material
formulation ranges from 25.degree. C. to 65.degree. C. or from
65.degree. C. to about 85.degree. C.
5. The method of claim 1, wherein a weight ratio between said
pre-catalysts ranges from 90:10 to 10:90.
6. The method of claim 5, wherein said weight ratio ranges from
60:40 to 40:60.
Description
FIELD AND BACKGROUND OF THE INVENTION
The present invention, in some embodiments thereof, relates to
three-dimensional inkjet printing and, more particularly, but not
exclusively, to systems, methods and compositions employing
ring-opening metathesis polymerization (ROMP) for producing
three-dimensional objects.
Three-dimensional (3D) inkjet printing is a known process for
building three dimensional objects by selectively jetting chemical
compositions, for example, polymerizable compositions, via ink-jet
printing head nozzles onto a printing tray in consecutive layers,
according to pre-determined image data. 3D inkjet printing is
performed by a layer by layer inkjet deposition of chemical
formulations, which form together a building material formulation.
Thus, a chemical formulation is dispensed in droplets from a
dispensing head having a set of nozzles to form layers on a
receiving medium. The layers may then be cured or solidified using
a suitable methodology, to form solidified or partially solidified
layers of the building material.
The chemical formulations used for forming the building material
may be initially liquid and subsequently hardened (cured or
solidified) to form the required layer shape. The hardening may be
effected, for example, by exposing the building material to a
curing energy such as thermal energy (e.g., by heating the building
material) or to irradiation (e.g., UV or other photo-irradiation),
or may be activated chemically, for example, by acid or base
activation.
The chemical (e.g., polymerizable) formulations utilized in inkjet
3D printing processes are therefore selected so as to meet the
process requirements, namely, exhibiting a suitable viscosity
during jetting (thus being non-curable under jetting conditions)
and rapid curing or solidification, typically upon exposure to a
stimulus, on the receiving medium. For example, when used with
currently available commercial print heads, the formulations should
have a relatively low viscosity, of about 10-25 cPs, at the jetting
temperature, in order to be jettable.
Various three-dimensional printing techniques exist and are
disclosed in, e.g., U.S. Pat. Nos. 6,259,962, 6,569,373, 6,658,314,
6,850,334, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510,
7,500,846, 7,962,237 and 9,031,680, all of the same Assignee, the
contents of which are hereby incorporated by reference.
In a 3D inkjet printing process such as Polyjet.TM. (Stratasys Ltd.
Israel), the building material is selectively jetted from one or
more printing heads and deposited onto a fabrication tray in
consecutive layers according to a pre-determined configuration as
defined by a software file.
A printing system utilized in a 3D inkjet printing process may
include a receiving medium and one or more printing heads. The
receiving medium can be, for example, a fabrication tray that may
include a horizontal surface to carry the material dispensed from
the printing head. The printing head(s) may be, for example, an ink
jet head having a plurality of dispensing nozzles arranged in an
array of one or more rows along the longitudinal axis of the
printing head. The jetting nozzles dispense material onto the
receiving medium to create the layers representing cross sections
of a 3D object.
In addition, there may be a source of curing energy, for curing the
dispensed building material.
Additionally, the printing system may include a leveling device for
leveling and/or establishing the height of each layer after
deposition and at least partial solidification, prior to the
deposition of a subsequent layer.
The building materials may include modeling materials and support
materials, which form the object and optionally the temporary
support constructions supporting the object as it is being built,
respectively.
The modeling material (which may include one or more material(s))
is deposited to produce the desired object/s and the support
material (which may include one or more material(s)) is used, with
or without modeling material elements, to provide support
structures for specific areas of the object during building and
assure adequate vertical placement of subsequent object layers,
e.g., in cases where objects include overhanging features or shapes
such as curved geometries, negative angles, voids, and so on.
Both the modeling and support materials are preferably liquid at
the working temperature at which they are dispensed, and
subsequently hardened, upon exposure to a condition that affects
curing of the materials, to form the required layer shape. After
printing completion, support structures are removed to reveal the
final shape of the fabricated 3D object.
In order to be compatible with most of the commercially-available
printing heads utilized in a 3D inkjet printing system, the uncured
building material should feature the following characteristics: a
relatively low viscosity (e.g., Brookfield Viscosity of up to 35
cps, preferably from 8 to 20 cps) at the working (e.g., jetting)
temperature; Surface tension of from about 10 to about 50 Dyne/cm;
and a Newtonian liquid behavior and high reactivity to a selected
curing energy, to enable immediate solidification of the jetted
layer upon activation (e.g., application of curing energy).
For example, a thin layer (5-40 microns) of the building material
should be sufficiently cured within about 200 milliseconds when
exposed to UV radiation (of 0.5 W/cm.sup.2, 340-390 nm), in order
to enable the building of subsequent layers.
When a cured rigid modeling material forms the final object, the
cured material should preferably exhibit heat deflection
temperature (HDT) which is higher than room temperature, in order
to assure its usability. Typically, the cured modeling material
should exhibit HDT of at least 35.degree. C. For an object to be
stable in variable conditions, a higher HDT is desirable.
Currently, the most commonly used building materials in 3D inkjet
printing are photocurable, particularly. UV-curable materials such
as acrylic based materials.
Currently available UV-curable modeling material formulations for
forming rigid objects by inkjet printing which exhibit the
properties required for 3D inkjet printing, while being jetted, as
described herein, are acrylic-based materials, which typically
exhibit HDT in the range of 35-50.degree. C. Exemplary such
formulations are generally described, for example, in U.S. Pat. No.
7,479,510, to the present Assignee.
Such modeling material formulations, when cured, typically feature
impact resistance in the range of 20-25 J/m.
While rigid objects, or parts thereof, fabricated by 3D inkjet
printing, should desirably exhibit good durability and stability, a
cured modeling material should feature both high HDT and high
toughness, i.e. impact resistance.
Ring-opening metathesis polymerization (ROMP) is a type of olefin
metathesis chain-growth polymerization. The driving force of the
reaction is the relief of strained cyclic structures, typically
cyclic olefins (e.g., norbornenes or cyclopentenes) or dienes
(e.g., cyclopentadiene-based compounds). The polymerization
reaction typically occurs in the presence of organometallic
catalysts, and the ROMP catalytic cycle involves formation of
metal-carbene species, which reacts with the double bond in the
cyclic structure to thereby form a highly strained
metallacyclobutane intermediate. The ring then opens, giving a
linear chain double bonded to the metal with a terminal double bond
as well. The as formed metal-carbene species then reacts with the
double bond on another cyclic monomer, and so forth.
During recent decades ROMP evolved as a powerful polymerization
tool especially due to the development of well-defined transition
metal complexes as catalysts. Ruthenium, molybdenum and osmium
carbene complexes useful as catalysts of ROMP reactions are
described, for example, in U.S. Pat. Nos. 5,312,940, 5,342,909,
5,728,917, 5,710,298, 5,831,108, and 6,001,909; and PCT
International Patent Applications having Publication Nos. WO
97/20865, WO 97/29135 and WO 99/51344.
The use of ROMP reactions in reaction injection molding (RIM) has
been described, for example, in U.S. Patent Application Publication
Nos. 2011/0171147, 2005/0691432, U.S. Pat. No. 8,487,046, EP Patent
Application Publication No. 2452958, and EP Patent No. 2280017. One
of the ROMP materials used in ROMP-based RIM is dicyclopentadiene
(DCPD).
Poly-DCPD-based materials exhibit good mechanical properties and
combine both good toughness and high thermal resistance. For
example, polymeric materials based on DCPD were used to produce
Telene 1810, which features a viscosity of about 200 cps at room
temperature, HDT of 120.degree. C. and impact of 300 J/m; and
Metton M15XX, which features a viscosity of 300 cps at room
temperature, Tg of 130.degree. C. and impact of 460 J/m [see, for
example,
www(dot)metton(dot)com/index(dot)php/metton-lmr/benefits].
Additional background art includes WO 2013/128452; Adv. Funct.
Mater. 2008, 18, 44-52; Adv. Mater. 2005, 17, 39-42; and Pastine,
S. J.; Okawa. D.; Zettl. A.; Frechet, J. M. J. J. Am. Chem. Soc.
2009, 131, 13586-13587; Vidavsky and Lemcoff, Beilstein J. Org.
Chem. 2010, 6, 1106-1119; Ben-Asuly et al., Organometallics 2009,
28, 4652-4655; Piermattei et al., Nature Chemistry, DOI:
10.1038/NCHEM.167; Szadkowska et al., Organometallics 2010, 29,
117-124; Diesendruck, C. E.; Vidavsky, Y.; Ben-Asuly, A.; Lemcoff,
N. G., J. Polym. Sci., Part A: Polym. Chem. 2009, 47, 4209-4213;
Wang et al., Angew. Chem. Int. Ed. 2008, 47, 3267-3270; U.S. Patent
Application Publication No. 2009-0156766; WO 2014/144634; EP Patent
No. 1757613; U.S. Pat. No. 8,519,069; U.S. Patent Application
Publication No. 2005/0040564 and PCT International Application No.
PCT/IL2015/051038 published as WO 2016/063282.
SUMMARY OF THE INVENTION
A need exists for a 3D inkjet printing technology which employs
curable materials that exhibit, upon curing, improved mechanical
performance, particularly a combination of high thermal resistance
and high toughness.
Ring Opening Metathesis Polymerization (ROMP) systems are used for
producing cured materials that exhibit valuable properties, such as
relatively low shrinkage, high thermal resistance, high impact, and
chemical and solvent resistance.
However, the ROMP technology is limited to methodologies such as,
for example, RIM, mainly due to its rapid curing at ambient
conditions (e.g., room temperature). Typically, a formulation
polymerizable by ROMP immediately solidifies once a catalyst is
added and/or activated. This limits the use of ROMP formulations in
3D inkjet processes, where liquid formulations that feature
viscosity within a pre-determined range are required to be passed
through inkjet printing heads.
The present inventors have now designed various methodologies which
enable using ROMP formulations in 3D inkjet printing.
Embodiments of the present invention therefore relate to
formulations and methods (processes) employing same which
efficiently allow practicing ROMP-based methodologies while meeting
the requirements of 3D inkjet printing processes.
According to an aspect of some embodiments of the present invention
there is provided a method of fabricating a three-dimensional
object, the method comprising sequentially forming a plurality of
layers in a configured pattern corresponding to the shape of the
object, thereby fabricating the object,
wherein the formation of each layer comprises dispensing at least
two modeling material formulations by at least two inkjet printing
heads, each head jetting one of the at least two modeling material
formulations, the at least two modeling material formulations
comprising an unsaturated cyclic monomer polymerizable by ring
opening metathesis polymerization (ROMP) and a catalyst system for
initiating ROMP of the monomer, the catalyst system comprising a
pre-catalyst and an activator for chemically activating the
catalyst towards initiating ROMP of the monomer, wherein at least
one of the modeling material formulations comprises the
pre-catalyst and at least another modeling material formulation
comprises the activator and is devoid of the pre-catalyst,
wherein the pre-catalyst is an acid-activatable Ruthenium-based
pre-catalyst and the activator is active towards chemically
activating the pre-catalyst.
According to some of any of the embodiments described herein, the
pre-catalyst comprises at least one bidentate Schiff base
ligand.
According to some of any of the embodiments described herein, the
Schiff base ligand is derived from a salicyldiamine derivative.
According to some of any of the embodiments described herein, the
pre-catalyst is represented by Formula I:
##STR00001##
wherein;
L.sub.1 and L.sub.2 are each independently selected from common
ligands of ruthenium-based catalysts for ROMP, such as a
nucleophilic carbene ligand and halogen, or, alternatively, one of
L.sub.1 and L.sub.2 is a bidentate Schiff base ligand, as described
herein;
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each
independently selected from the group consisting of hydrogen,
halogen, alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl,
heteroaryl, alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl,
alkylamino, alkylthio, aminosulfonyl, monoalkylaminosulfonyl,
dialkylaminosulfonyl, alkylsulfonyl, nitrile, nitro, alkylsulfinyl,
trihaloalkyl, perfluoroalkyl, carboxylic acid, ketone, aldehyde,
nitrate, cyano, isocyanate, thioisocyanate, cyanato, thiocyanato,
hydroxyl, ester, ether, thioether, amine, alkylamine, imine, amide,
halogen-substituted amide, trifluoroamide, sulfide, disulfide,
sulfonate, carbamate, silane, siloxane, phosphine, phosphate,
borate, or -A-Fn, wherein "A" is absent or is a divalent
hydrocarbon moiety selected from alkylene and arylalkylene, wherein
the alkyl portion of the alkylene and arylalkylene groups can be
linear or branched, saturated or unsaturated, cyclic or acyclic,
and substituted or unsubstituted, wherein the aryl portion of the
arylalkylene can be substituted or unsubstituted, and wherein
hetero atoms and/or functional groups may be present in either the
aryl or the alkyl portions of the alkylene and arylalkylene groups,
and Fn is any one or more of the R.sub.1, R.sub.2, R.sub.3,
R.sub.4, R.sub.5 and R.sub.6 which may be linked together to form a
cyclic group;
R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are each independently
selected from the group consisting of hydrogen, halogen, alkyl,
alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl, heteroaryl,
alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl, alkylamino,
alkylthio, aminosulfonyl, monoalkylaminosulfonyl,
dialkylaminosulfonyl, alkylsulfonyl, nitrile, nitro, alkylsulfinyl,
trihaloalkyl, perfluoroalkyl, carboxylic acid, ketone, aldehyde,
nitrate, cyano, isocyanate, thioisocyanate, cyanato, thiocyanato,
hydroxyl, ester, ether, thioether, amine, alkylamine, imine, amide,
halogen-substituted amide, trifluoroamide, sulfide, disulfide,
sulfonate, carbamate, silane, siloxane, phosphine, phosphate, and
borate, or, alternatively, two of R.sub.7-R.sub.10 form together a
cyclic ring.
According to some of any of the embodiments described herein,
R.sub.1, R.sub.2, R.sub.3 and R.sub.4 form together a cyclic ring,
preferably an aromatic ring (e.g., phenyl).
According to some of any of the embodiments described herein,
R.sub.5 is an aryl (e.g., phenyl).
According to some of any of the embodiments described herein,
R.sub.10 is an aryl (e.g., phenyl).
According to some of any of the embodiments described herein, two
of R.sub.7, R.sub.8 and R.sub.9 form a cyclic ring, preferably an
aromatic ring (e.g., phenyl).
According to some of any of the embodiments described herein.
L.sub.1 is a nucleophilic carbene ligand, preferably a carbene
ligand represented by the Formula:
##STR00002##
wherein Ra and Rb are each independently alkyl, cycloalkyl or aryl
(e.g., phenyl).
According to some of any of the embodiments described herein.
L.sub.2 is halogen (e.g., chloro).
According to some of any of the embodiments described herein, the
pre-catalysts is represented by Formula II:
##STR00003##
wherein Rc and Rd each independently represent one or more
substituents which are each independently as defined herein for
R.sub.7-R.sub.9.
According to some of any of the embodiments described herein, one
of L.sub.1 and L.sub.2 is the bidentate Schiff base ligand.
According to some of any of the embodiments described herein,
L.sub.1 is a nucleophilic carbene ligand and L.sub.2 is the
bidentate Schiff base ligand.
According to some of any of the embodiments described herein, the
pre-catalyst is represented by the Formula III:
##STR00004##
wherein Rc and Rd are as defined herein, and Re and Rf are as
defined herein for Rc and Rd.
According to some of any of the embodiments described herein, the
pre-catalyst is selected from the group of pre-catalysts presented
in Table B.
According to some of any of the embodiments described herein, the
pre-catalyst comprises at least two pre-catalysts, each being
independently represented by Formulae I, II or III, as defined
herein.
According to some of any of the embodiments described herein, one
of the pre-catalysts is represented by Formula I, wherein L.sub.1
is a nucleophilic carbene ligand and L.sub.2 is halogen, and
another one of the pre-catalysts is represented by Formula I,
wherein L.sub.1 is a nucleophilic carbene ligand and L.sub.2 is a
bidentate Schiff base ligand.
According to some of any of the embodiments described herein, one
of the pre-catalysts is represented by Formula II and one of the
pre-catalysts is represented by Formula III.
According to some of any of the embodiments described herein, a
ratio between the two pre-catalysts ranges from 90:10 to 10:90, or
from 80:20 to 20:80, or from 60:40 to 40:60.
According to an aspect of some embodiments of the present invention
there is provided a method of fabricating a three-dimensional
object, the method comprising sequentially forming a plurality of
layers in a configured pattern corresponding to the shape of the
object, thereby fabricating the object,
wherein the formation of each layer comprises dispensing at least
two modeling material formulations by at least two inkjet printing
heads, each head jetting one of the at least two modeling material
formulations, the at least two modeling material formulations
comprising an unsaturated cyclic monomer polymerizable by ring
opening metathesis polymerization (ROMP) and a catalyst system for
initiating ROMP of the monomer, the catalyst system comprising a
pre-catalyst and an activator for chemically activating the
catalyst towards initiating ROMP of the monomer, wherein at least
one of the modeling material formulations comprises the
pre-catalyst and at least another modeling material formulation
comprises the activator and is devoid of the pre-catalyst,
wherein the pre-catalyst comprises at least one pre-catalyst
represented by Formula II as defined herein and at least one
catalyst represented by Formula II as defined herein.
According to some of any of the embodiments described herein, a
ratio between the two pre-catalysts ranges from 90:10 to 10:90, or
from 80:20 to 20:80, or from 60:40 to 40:60.
According to some of any of the embodiments described herein, the
activator is active towards chemically activating the
pre-catalyst.
According to some of any of the embodiments described herein, a
total concentration of the pre-catalyst ranges from 0.0001 to 0.5%,
or from 0.01 to 0.1%, or from 0.03 to 0.06%, by weight, of the
total weight of the modeling material formulation comprising
same.
According to some of any of the embodiments described herein, the
activator is represented by the Formula:
(R).sub.nSi(Cl).sub.4-n
wherein:
n is 1, 2, or 3, and R is selected from hydrogen, alkyl and aryl,
such that when n is 2 or 3, each R can be the same or different,
and such that at least one R is alkyl or aryl.
According to some of any of the embodiments described herein, the
activator is selected from the group of activators presented in
Table C.
According to some of any of the embodiments described herein, the
activator is selected from trichlorododecyl silane (TCSA),
trichloro(phenyl)silane and chlorodimethylphenyl silane.
According to some of any of the embodiments described herein, a
concentration of the activator ranges from 0.002 to 2%, or from
0.01 to 1%, by weight, of the total weight of the modeling material
formulation comprising the activator.
According to some of any of the embodiments described herein, each
of the modeling material formulations is characterized by a
viscosity of no more than 35 centipoises at a temperature of the
inkjet printing head during the dispensing.
According to some of any of the embodiments described herein, at
least one of the formulations comprises the monomer and the
activator and at least another one of the formulations comprises
the monomer and the pre-catalyst.
According to some of any of the embodiments described herein, at
least one of the formulations comprises a ROMP inhibitor.
According to some of any of the embodiments described herein, at
least one of the modeling material formulations comprises a ROMP
monomer, the pre-catalyst and a ROMP inhibitor and at least another
one of the modeling material formulations comprises a ROMP monomer
and the activator.
According to some of any of the embodiments described herein, a
concentration of the ROMP inhibitor ranges from 1 to 200 ppm, or
from 1 to 60 ppm, or from 1 to 20 ppm, or from 10 to 20 ppm, of the
total weight of a modeling material formulation comprising
same.
According to some of any of the embodiments described herein, at
least one of the modeling material formulations further comprises
toughening agent (e.g., an impact modifying agent).
According to some of any of the embodiments described herein, each
of the modeling material formulations further comprises a
toughening agent (e.g., an impact modifying agent).
According to some of any of the embodiments described herein, the
toughening agent is an elastomer (an elastomeric material), and in
some embodiments, it is a low molecular elastomer or otherwise an
elastomer as described herein in any of the respective
embodiments.
According to some of any of the embodiments described herein, a
concentration of the toughening agent ranges from 1 to 20%, or from
1 to 10%, or from 5 to 10%, by weight, of a modeling material
comprising same.
According to some of any of the embodiments described herein, a
modeling material formulation that comprises the pre-catalyst
further comprises an antioxidant.
According to some of any of the embodiments described herein, a
modeling material that comprises the pre-catalyst further comprises
a proton donor.
According to some of any of the embodiments described herein, the
method further comprises heating each of the layers following the
dispensing.
According to some of any of the embodiments described herein, the
heating is by infrared radiation.
According to some of any of the embodiments described herein, the
heating is by a ceramic radiation source.
According to some of any of the embodiments described herein, the
dispensing is in a chamber, and wherein the heating comprises
heating the chamber to a temperature of from 25.degree. C. to
65.degree. C.
According to some of any of the embodiments described herein, the
plurality of layers are formed on a working tray, the method
comprising heating the working tray to a temperature of from
25.degree. C. to 65.degree. C.
According to some of any of the embodiments described herein, the
heating is to a temperature of about 50.degree. C.
According to some of any of the embodiments described herein, for
at least one layer, two different modeling material formulations
are dispensed at adjacent locations within (or over) the layer.
According to some of any of the embodiments described herein, the
method further comprises dispensing a support material formulation
by at least one additional inkjet printing head.
According to some of any of the embodiments described herein, the
method further comprises exposing the support material formulation
to a condition for inducing polymerization or curing of the support
material formulation.
According to some of any of the embodiments described herein, a
temperature of an inkjet printing head for dispensing the at least
one modeling material formulation ranges from 25.degree. C. to
65.degree. C.
According to some of any of the embodiments described herein, a
temperature of an inkjet printing head for dispensing the at least
one modeling material formulation ranges from 65.degree. C. to
about 85.degree. C.
According to some of any of the embodiments described herein, the
dispensing and/or the exposing are performed under inert
atmosphere.
According to some of any of the embodiments described herein, the
method further comprises straightening the layer by a leveling
device.
According to some of any of the embodiments described herein, the
method further comprises removing cured or partially cured
formulation off the leveling device.
According to some of any of the embodiments described herein, the
straightening is while the at least one formulation is at a cured
or partially cured or uncured state.
According to some of any of the embodiments described herein, the
straightening comprises milling.
According to an aspect of some embodiments of the present invention
there is provided a kit, usable in a method as described herein.
According to an aspect of some embodiments of the present invention
there is provided a kit comprising at least two modeling material
formulations as described herein in any of the respective
embodiments, each of the formulations being individually packaged
within the kit, as described in further detail hereinbelow. In some
embodiments, the kit comprises the at least two modeling material
formulations, and is identified for use, or is for use, in 3D
inkjet printing of an object. In some embodiments, the kit
comprises instructions to use the at least two modeling material
formulations for manufacturing a 3D object by 3D inkjet
printing.
Unless otherwise defined, all technical and/or scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention pertains. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of embodiments of the
invention, exemplary methods and/or materials are described below.
In case of conflict, the patent specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and are not intended to be
necessarily limiting.
Implementation of the method and/or system of embodiments of the
invention can involve performing or completing selected tasks
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of embodiments of
the method and/or system of the invention, several selected tasks
could be implemented by hardware, by software or by firmware or by
a combination thereof using an operating system.
For example, hardware for performing selected tasks according to
embodiments of the invention could be implemented as a chip or a
circuit. As software, selected tasks according to embodiments of
the invention could be implemented as a plurality of software
instructions being executed by a computer using any suitable
operating system. In an exemplary embodiment of the invention, one
or more tasks according to exemplary embodiments of method and/or
system as described herein are performed by a data processor, such
as a computing platform for executing a plurality of instructions.
Optionally, the data processor includes a volatile memory for
storing instructions and/or data and/or a non-volatile storage, for
example, a magnetic hard-disk and/or removable media, for storing
instructions and/or data. Optionally, a network connection is
provided as well. A display and/or a user input device such as a
keyboard or mouse are optionally provided as well.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Some embodiments of the invention are herein described, by way of
example only, with reference to the accompanying drawings. With
specific reference now to the drawings in detail, it is stressed
that the particulars shown are by way of example and for purposes
of illustrative discussion of embodiments of the invention. In this
regard, the description taken with the drawings makes apparent to
those skilled in the art how embodiments of the invention may be
practiced.
In the drawings:
FIG. 1 is a flowchart describing an exemplary method according to
some embodiments of the present invention;
FIG. 2 is a schematic illustration of a system suitable for 3D
inkjet printing of an object according to some embodiments of the
present invention;
FIGS. 3A-C are schematic illustrations of printing heads according
to some embodiments of the present invention; and
FIG. 4 is a schematic illustration of a self-cleaning leveling
device, according to some embodiments of the present invention.
FIGS. 5A and 5B present schematic illustrations of bitmaps in
embodiments of the invention in which a "Drop on Drop" printing
protocol is employed. A bitmap suitable for the deposition of the
first model formulation is illustrated in FIG. 5A and a bitmap
suitable for the deposition of the second model formulation is
illustrated in FIG. 5B. When the droplets of both formulations have
the same or approximately the same weight, the bitmaps are useful
for a 50:50 (or 1:1) w/w ratio. White boxes represent vacant
locations, dotted boxes represent droplets of the first model
formulation and wavy boxes represent droplets of the second model
formulation. Each patterned (wavy/dotted) box represents a pixel
(e.g., one composition droplet) in a layer. Both model formulations
can be deposited at the same location, but at different times,
during movement of the printing heads.
FIGS. 6A and 6B present schematic illustrations of bitmaps in
embodiments of the invention in which a "side-by-side" printing
protocol is employed. A bitmap suitable for the deposition of the
first model formulation is illustrated in FIG. 6A and a bitmap
suitable for the deposition of the second model formulation is
illustrated in FIG. 6B. When the droplets of both formulations have
the same or approximately the same weight, the bitmaps are useful
for a 50:50 (or 1:1) w/w ratio. White boxes represent vacant
locations, dotted boxes represent droplets of the first model
formulation and wavy boxes represent droplets of the second model
formulation. Each patterned (wavy/dotted) box represents a pixel
(e.g., one formulation droplet). A drop of the first model
formulation (dotted boxes) is deposited adjacent to a drop of the
second model formulation (wavy boxes). Both model formulations may
be deposited simultaneously during movement of the printing
heads.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
The present invention, in some embodiments thereof, relates to
three-dimensional inkjet printing and, more particularly, but not
exclusively, to systems, methods and compositions employing
ring-opening metathesis polymerization (ROMP) for producing
three-dimensional objects.
Before explaining at least one embodiment of the invention in
detail, it is to be understood that the invention is not
necessarily limited in its application to the details of
construction and the arrangement of the components and/or methods
set forth in the following description and/or illustrated in the
drawings and/or the Examples. The invention is capable of other
embodiments or of being practiced or carried out in various
ways.
The present inventors have sought for methodologies that enable
utilizing materials obtained via ring opening metathesis
polymerization (ROMP) in three-dimensional (3D) inkjet printing
processes.
As discussed hereinabove, 3D inkjet printing systems require, on
one hand, using building material formulations which exhibit
certain properties while being dispensed from inkjet printing
heads, and, on the other hand, aim to obtain three-dimensional
objects which feature stability, durability and toughness.
Most of the currently available 3D inkjet printing processes
utilize photocurable (e.g., UV curable) formulations. These
formulations, while meeting the requirements of suitable viscosity
at the jetting temperature and a rapid hardening upon exposure to
irradiation, often provide objects with mechanical properties that
are less than desired.
Materials obtained by ring-opening metathesis polymerization (ROMP)
are characterized by exceptional mechanical and other properties.
However, employing ROMP chemistry in 3D inkjet printing requires
solving problems associated with, for example, fast propagation of
the polymerization reaction, immediately once a catalyst contacts a
ROMP monomer. Thus, for example, pre-mixing a ROMP monomer and a
ROMP catalyst before jetting leads to substantial increase in
viscosity when such a formulation passes through the inkjet
printing head and nozzle plate, resulting in clogging due to
polymerization of the composition on the nozzle plate. Other
methodologies aimed at separately jetting a ROMP catalyst and a
ROMP monomer were found by the present inventors to result in
insufficient reactivity of the ROMP system or in models featuring
physic-mechanical properties that do not meet the common
requirements.
The present inventors have now designed and successfully practiced
novel methodologies for utilizing the valuable properties of
materials prepared by ROMP in the fabrication of three-dimensional
objects which feature exceptional physic-mechanical properties in
3D inkjet printing processes.
The Method:
According to aspects of some embodiments of the present invention,
there is provided a method of three-dimensional (3D) inkjet
printing of a three-dimensional object. According to embodiments of
these aspects, the method is effected by sequentially forming a
plurality of layers in a configured pattern corresponding to the
shape of the object, thereby forming the object.
According to embodiments of these aspects, formation of each layer
is effected by dispensing at least one building material
formulation (uncured building material), and exposing the dispensed
building material formulation to a condition which affects curing
of the formulation to thereby obtain a cured building material.
The method and system of the present embodiments manufacture
three-dimensional objects based on computer object data in a
layerwise manner by forming a plurality of layers in a configured
pattern corresponding to the shape of the objects. The computer
object data can be in any known format, including, without
limitation, a Standard Tessellation Language (STL) or a
StereoLithography Contour (SLC) format, Virtual Reality Modeling
Language (VRML). Additive Manufacturing File (AMF) format, Drawing
Exchange Format (DXF), Polygon File Format (PLY) or any other
format suitable for Computer-Aided Design (CAD).
Each layer is preferably formed by three-dimensional inkjet
printing which scans a two-dimensional surface and patterns it.
While scanning, the apparatus visits a plurality of target
locations on the two-dimensional layer or surface, and decides, for
each target location or a group of target locations, whether or not
the target location or group of target locations is to be occupied
by building material, and which type of building material is to be
delivered thereto. The decision is made according to a computer
image of the surface.
When three-dimensional inkjet printing is employed, a building
material (uncured) is dispensed from a dispensing head having a set
of nozzles to deposit the building material in layers on a
supporting structure. The inkjet printing system thus dispenses
building material in target locations which are to be occupied and
leaves other target locations void. The inkjet printing typically
includes a plurality of dispensing heads, each of which can be
configured to dispense a different building material formulation.
Thus, different target locations can be occupied by different
building materials.
The types of building materials can be categorized into two major
categories: modeling material and support material. The support
material serves as a supporting matrix or construction for
supporting the object or object parts during the fabrication
process and/or other purposes, e.g., providing hollow or porous
objects. Support constructions may additionally include modeling
material elements, e.g., for further support strength.
Herein throughout, the phrases "building material formulation",
"uncured building material", "uncured building material
formulation", "building material" and other variations therefore
collectively describe the materials that are dispensed to
sequentially form the layers, as described herein. This phrase
encompasses uncured materials dispensed so as to form the object,
namely, one or more uncured modeling material formulation(s), and
uncured materials dispensed so as to form the support, namely
uncured support material formulations.
Herein, the phrase "printed object" describes a product of the
additive manufacturing process (e.g., a 3D inkjet process), before
the support material, if such has been used as part of the uncured
building material, is removed.
Herein throughout, the term "object" or "model object" describes a
final product of the additive manufacturing. This term refers to
the product obtained by a method as described herein, after removal
of the support material, if such has been used as part of the
uncured building material. The "object" therefore essentially
consists (e.g., at least 95 weight percents) of a cured modeling
material.
The term "object" as used herein throughout refers to a whole
object or a part thereof.
Herein throughout, the phrase "cured modeling material" describes
the part of the building material that forms the object, as defined
herein, upon exposing the dispensed building material to curing
(and optionally post-curing treatment), and, optionally, if a
support material has been dispensed, removal of the cured support
material, as described herein. The cured modeling material can be a
single cured material or a mixture of two or more cured materials,
depending on the modeling material formulations used in the method,
as described herein.
The phrase "cured modeling material" or "cured modeling material
formulation" can be regarded as a cured building material wherein
the building material consists only of a modeling material
formulation (and not of a support material formulation). That is,
this phrase refers to the portion of the building material, which
is used to provide the final object.
Herein throughout, the phrase "modeling material formulation",
which is also referred to herein interchangeably as "modeling
formulation", "modeling material" "model material" or simply as
"formulation", describes a part or all of the uncured building
material which is dispensed so as to form the object, as described
herein. The modeling material formulation is an uncured modeling
formulation (unless specifically indicated otherwise), which, upon
exposure to a condition that effects curing (and optionally
post-curing treatment), forms the object or a part thereof.
In some embodiments of the present invention, a modeling material
formulation is formulated for use in three-dimensional inkjet
printing and is able to form a three-dimensional object on its own.
i.e., without having to be mixed or combined with any other
substance.
An uncured building material can comprise one or more modeling
materials, and can be dispensed such that different parts of the
object are made, upon curing, of different cured modeling
formulations, and hence are made of different cured modeling
materials or different mixtures of cured modeling materials.
The method of the present embodiments manufactures
three-dimensional objects in a layerwise manner by forming a
plurality of layers in a configured pattern corresponding to the
shape of the objects, as described herein.
The printed three-dimensional object is made of the modeling
material or a combination of modeling materials or a combination of
modeling material/s and support material/s or modification thereof
(e.g., following curing). All these operations are well-known to
those skilled in the art of solid freeform fabrication.
In some exemplary embodiments of the invention an object is
manufactured by dispensing a building material that comprises two
or more different modeling material formulations, each modeling
material formulation from a different dispensing head of the inkjet
printing apparatus. The modeling material formulations are
optionally and preferably deposited in layers during the same pass
of the printing heads. The modeling material formulations and/or
combination of formulations within the layer are selected according
to the desired properties of the object.
FIG. 1 presents a flowchart describing an exemplary method
according to some embodiments of the present invention. It is to be
understood that, unless otherwise defined, the operations described
hereinbelow can be executed either contemporaneously or
sequentially in many combinations or orders of execution.
Specifically, the ordering of the flowchart is not to be considered
as limiting. For example, two or more operations, appearing in the
following description or in the flowchart diagrams in a particular
order, can be executed in a different order (e.g., a reverse order)
or substantially contemporaneously. Additionally, several
operations described below are optional and may not be
executed.
The method begins at 10 and optionally and preferably continues to
11 at which 3D printing data corresponding to the shape of the
object are received. The data can be received, for example, from a
host computer which transmits digital data pertaining to
fabrication instructions based on computer object data, e.g., in a
form of a Standard Tessellation Language (STL) or a
StereoLithography Contour (SLC) format, Virtual Reality Modeling
Language (VRML), Additive Manufacturing File (AMF) format. Drawing
Exchange Format (DXF), Polygon File Format (PLY) or any other
format suitable for Computer-Aided Design (CAD).
The method continues to 12 at which droplets of a building material
as described herein are dispensed in layers, on a receiving medium,
using at least two different multi-nozzle inkjet printing heads,
according to the printing data. The receiving medium can be a tray
of a three-dimensional inkjet system or a previously deposited
layer. The building material comprises two or more modeling
material formulations that can undergo polymerization via ROMP, as
described herein. The building material can optionally further
comprise a support material formulation.
In some embodiments of the present invention, the dispensing 12 is
effected within an environment that is similar in its thermodynamic
condition (for example, temperature, humidity, pressure) to the
ambient environment. Alternatively, the dispensing 12 can be
executed in a generally dry (e.g., relative humidity of less than
60% or less than 50% or less than 40%, or less) and inert
environment. For example, the dispensing can be executed in a
nitrogen environment. In these embodiments, dispensing 12 is
executed in a chamber and is optionally and preferably preceded by
an operation in which an inert gas, e.g., nitrogen, helium, krypton
and the like is introduced into the chamber. Also contemplated is
the use of a drying agent. Representative examples of drying agents
suitable for the present embodiments include, without limitation,
calcium chloride, calcium sulfide and silica gel.
Optionally, before being dispensed, the uncured building material,
or a part thereof (e.g., one or more formulations of the building
material), is heated, prior to being dispensed. These embodiments
are particularly useful for uncured building material formulations
having relatively high viscosity at the operation temperature of
the working chamber of a 3D inkjet printing system. The heating of
the formulation(s) is preferably to a temperature that allows
jetting the respective formulation through a nozzle of a printing
head of a 3D inkjet printing system. In some embodiments of the
present invention, the heating is to a temperature at which the
respective formulation exhibits a viscosity of no more than X
centipoises, where X is about 40 centipoises, or about 35
centipoises, or about 30 centipoises, preferably about 25
centipoises and more preferably about 20 centipoises, or 18
centipoises, or 16 centipoises, or 14 centipoises, or 12
centipoises, or 10 centipoises and even as low as 2
centipoises.
The heating can be executed before loading the respective
formulation into the printing head of the 3D printing system, or
while the formulation is in the printing head or while the
formulation passes through the nozzle of the printing head.
In some embodiments, the heating is executed before loading of the
respective formulation into the printing head, so as to avoid
clogging of the printing head by the formulation in case its
viscosity is too high.
In some embodiments, the heating is executed by heating the
printing heads, at least while passing the formulations making up
the building material through the nozzle of the printing head.
In some embodiments, a temperature of an inkjet printing head for
dispensing a modeling material formulation as described herein is
lower than 70.degree. C., and ranges, for example, from about
25.degree. C. to about 65.degree. C., including any subranges and
intermediate values therebetween. Modeling material formulations
which comprise one or more monomers that undergo polymerization via
ROMP, as described herein, and optionally other, non-curable
components, are suitable for use in the context of these
embodiments.
In some embodiments, higher temperatures of an inkjet printing head
are required, for example, higher than 70.degree. C. or ranging
from about 65.degree. C. to about 95.degree. C., including any
subranges and intermediate values therebetween.
Once the uncured building material is dispensed on the receiving
medium according to the 3D printing data, the method optionally and
preferably continues to 13 at which the deposited layers are
exposed to a condition (or two or more conditions) that induces
ROMP, as defined herein (e.g., a curing condition). Preferably,
each individual layer is exposed to this condition following or
during the deposition of the layer, and prior to the deposition of
the subsequent layer.
In some embodiments, exposing to a condition that induces ROMP
(e.g., a curing condition) is performed under a generally dry and
inert environment, as described herein.
In these embodiments, the dry and inert environment is optionally
and preferably prepared before the material is dispensed so that 13
can be executed simultaneously with 12 wherein the material is
exposed to the environment upon exiting the inkjet printing
head.
Alternatively, the exposure 13 can include exposing the dispensed
layer to radiation, such as, but not limited to, electromagnetic
radiation, for example, infrared radiation (e.g., at a wavelength
of from about 800 nm to about 4 .mu.m), ultraviolet radiation
(e.g., at a wavelength of from about 200 nm to about 400 nm) and
visible or near-visible light radiation (e.g., at a wavelength of
from about 400 nm to about 800 nm), or particle radiation, for
example in the form of an electron beam, depending on the modeling
material being used. Preferably, but not necessarily, the infrared
radiation is applied by a ceramic lamp, for example, a ceramic lamp
that produces infrared radiation of from about 2.4 .mu.m to about
4.3 .mu.m, or from about 3 .mu.m to about 4 .mu.m, e.g. about 3.5
.mu.m, or of any other wavelength suitable for efficient
application of heat, as discussed hereafter. Alternatively or
additionally, the exposure 13 can include exposing the dispensed
layer to elevated temperature (for example, from about 25.degree.
C. to about 100.degree. C., or from about 40.degree. C. to about
100.degree. C., or from about 25.degree. C. to about 65.degree. C.,
or from about 35.degree. C. to about 50.degree. C. or of about
50.degree. C.). Higher temperatures (for example, above 100.degree.
C. or from about 100.degree. C. to about 900.degree. C., or from
about 200.degree. C. to about 900.degree. C., e.g., about
300.degree. C., or from about 300.degree. C. to about 900.degree.
C. or from about 400.degree. C. to about 900.degree. C.) are also
contemplated. The elevated temperatures can be generated by heating
the tray on which the layers are dispensed, and/or the chamber
within which the printing process is executed or by heat-inducing
irradiation, using a radiation source as described herein, at a
suitable wavelength for providing a required temperature. A ceramic
lamp, for example, when operated at the above-described
wavelengths, may result in heating a dispensed formulation to up to
300.degree. C., and even to a temperature of from about 400.degree.
C. to about 900.degree. C.
The method can preferably continue to 14 at which the deposited
layer is straightened, for example, by a leveling device.
Optionally, the layer is straightened after the dispensed
formulation is cured (e.g., exposed to a curing condition, for
example, heat). Alternatively, the layer is straightened while the
dispensed formulation is still uncured. In some embodiments,
straightening of a layer is performed so as to provide a certain
(e.g., pre-determined) thickness of the layer, to thereby provide a
plurality of layers in which a thickness of at least one, and
preferably two or more, of the layers is controlled.
As used herein the phrase "cured" refers to a formulation that
underwent curing or at least a partial curing, as defined herein,
and encompasses a state of the formulation in which at least 20% or
at least 30% or at least 40% or at least 50% or at least 60% or at
least 70% of the formulation underwent curing, as defined herein,
and a state of a formulation that underwent up to 100% curing.
Typically, a formulation that underwent curing or partial curing is
characterized by a viscosity that is substantially higher than an
uncured formulation, and preferably, a formulation, or at least a
part thereof, solidifies upon curing. A "cured" formulation is also
referred to interchangeably as a "hardened" formulation or as a
"solidified" formulation.
Straightening or leveling of a layer or layers after curing (or
partial curing) can be achieved by a leveling device that is
capable of reforming the solidified portion of the formulation or
removing part thereof. A representative example of such a leveling
device is a roller capable of milling, grinding and/or flaking a
solidified formulation or part thereof. Straightening can be
achieved by a leveling device that is capable of leveling the
formulation in its liquid, gel, partially-cured or cured state.
In some embodiments, the leveling device effects milling, grinding
and/or flaking, and/or removes at least part of the top of a layer
of the formulation. Such a leveling device can be, for example, a
roller, a blade or a cutter.
In some embodiments of the present invention the method continues
to 15 at which cured, partially cured or uncured formulation is
removed off the leveling device. These embodiments are particularly
useful when the leveling device is applied to the layer while the
formulation is uncured or partially cured. In this case, a portion
of the formulation collected by the leveling device can experience
curing or partial curing while the formulation is on the leveling
device (for example on the roller, when the leveling device
comprises a roller), and the method preferably removes such cured
or partially cured formulation from the device.
These embodiments can also be useful when the leveling device is
applied to the layer while the formulation is cured (for example,
when the leveling device effects milling, grinding flaking and/or
removing part of the solidified portion of the formulation). In
this case the method removes the debris of the milling, grinding,
flaking or material removal process from the leveling device, using
for example a suction device.
Operation 15 is preferably executed automatically and optionally
also continuously while the leveling device is in motion over the
layer. For example, the leveling device can comprise a double
roller having a first roller that contacts and straightens the
layer and a second roller that is in contact with the first roller
but not with the layer and which is configured to remove the
formulation from the first roller.
In some embodiments, the method continues to 16 at which remnant
formulations are removed also from the surface of the dispensing
heads, for example, via a wipe operation that can be executed at
predetermined time intervals, for example, once the head completes
a movement along the scanning direction or a cycle of reciprocal
movements along the scanning direction. The wiping can be by a
blade, or more preferably, a wet fabric.
In some embodiments, the method continues to 17 at which remnant
formulations are purged out of the dispensing heads at a dedicated
location on the tray that is laterally displaced from the location
at which the object is being built.
The method ends at 18.
In some of any of the embodiments described herein, the building
material comprises two or more modeling material formulations, as
described in further detail hereinafter, and dispensing the
building material comprises dispensing two or more modeling
material formulations.
To ensure reaction between the first and second modeling material
formulations, the deposition of the compositions can be performed
in more than one way.
In some embodiments of the present invention a "Drop on Drop"
printing protocol is employed. These embodiments are schematically
illustrated in FIGS. 5A and 5B. A bitmap suitable for the
deposition of the first modeling material formulation is
illustrated in FIG. 5A and a bitmap suitable for the deposition of
the second modeling material formulation is illustrated in FIG. 5B.
White boxes represent vacant locations, dotted boxes represent
droplets of the first modeling material formulation and wavy boxes
represent droplets of the second modeling material formulation. The
printing data in these embodiments are such that for each layer,
both modeling material formulations are deposited at the same
location, but different times, during movement of the printing
head. For example, each droplet of a first modeling material
formulation can be jetted on top of a droplet of a second modeling
material formulation, or vice versa. Preferably, but not
necessarily, the two formulation parts are jetted in drops at the
same weight and/or rate. These embodiments are particularly useful
when the desired weight ratio is 1:1. For other desired weight
ratios, the two formulation parts are preferably jetted in drops of
different weights, wherein the ratio of the weights corresponds to
the desired ratio.
A representative example for a resolution suitable for the present
embodiments is 1200 dpi in the X direction and 300 dpi in the Y
direction. The drop on drop printing protocol allows the two types
of drops to combine and mix before the crystallization of deposited
material.
In some embodiments of the present invention a "side by side"
printing protocol is employed. These embodiments are schematically
illustrated in FIGS. 6A and 6B. A bitmap suitable for the
deposition of the first modeling material formulation is
illustrated in FIG. 6A and a bitmap suitable for the deposition of
the second modeling material formulation is illustrated in FIG. 6B.
The colors of the white, dotted and wavy boxes represent vacant
locations, droplets of the first modeling material formulation and
droplets of the second modeling material formulation, respectively.
The printing data in these embodiments is such that for each layer,
each drop of a first modeling material formulation is jetted
adjacent to a drop of a second modeling material formulation, or
vice versa. Due to drop spreading, the adjacent drops tend to
partially overlap. As a result, the two drops diffuse toward each
other, mix and interact after deposition.
In the schematic illustrations shown in FIGS. 5A-6B, chessboard
bitmaps are illustrated, but this need not necessarily be the case,
since, for some applications, other bitmap patterns can be
employed.
In some of any of the embodiments described herein, the building
material further comprises one or more support material
formulations.
In some of any of the embodiments described herein, dispensing a
building material further comprises dispensing the support material
formulation(s).
Dispensing the support material formulation, in some embodiments,
is effected by inkjet printing head(s) other than the inkjet
printing heads used for dispensing the modeling material
formulation(s).
In some embodiments, exposing the building material to a condition
that induces curing includes one or more conditions that affect
curing of a support material formulation, to thereby obtain a cured
support material.
In some of any of the embodiments described herein, once a building
material is cured, the method further comprises removing the cured
support material. Any of the methods usable for removing a support
material formulation can be used, depending on the materials
employed in the modeling material formulation and the support
material formulation. Such methods include, for example, mechanical
removal of the cured support material and/or chemical removal of
the cured support material by contacting the cured support material
with a solution in which it is dissolvable (e.g., an alkaline
aqueous solution).
As used herein, the term "curing" describes a process in which a
formulation is hardened. This term encompasses polymerization of
monomer(s) and/or oligomer(s) and/or cross-linking of polymeric
chains (either of a polymer present before curing or of a polymeric
material formed in a polymerization of the monomers or oligomers).
The product of a curing reaction is therefore typically a polymeric
material and in some cases a cross-linked polymeric material. This
term, as used herein, encompasses also partial curing, for example,
curing of at least 20% or at least 30% or at least 40% or at least
50% or at least 60% or at least 70% of the formulation, as well as
100% of the formulation.
Herein, the phrase "a condition that affects curing" or "a
condition for inducing curing", which is also referred to herein
interchangeably as "curing condition" or "curing inducing
condition" describes a condition which, when applied to a
formulation that contains a curable material, induces
polymerization of monomer(s) and/or oligomer(s) and/or
cross-linking of polymeric chains. Such a condition can include,
for example, application of a curing energy, as described
hereinafter to the curable material(s), and/or contacting the
curable material(s) (e.g., ROMP monomer) with chemically reactive
components such as other components of a ROMP catalyst system, as
described in further detail hereinafter.
In some embodiments, the curing condition comprises generating an
active ROMP catalyst, e.g., activating a pre-catalyst by contacting
it with a suitable activator), optionally in combination with
application of a curing energy (e.g., heat).
When a condition that induces curing comprises application of a
curing energy, the phrase "exposing to a condition that affects
curing" means that the dispensed layers are exposed to the curing
energy and the exposure is typically performed by applying a curing
energy to the dispensed layers.
A "curing energy" typically includes application of radiation or
application of heat.
The radiation can be electromagnetic radiation (e.g., ultraviolet
or visible light), or electron beam radiation, or ultrasound
radiation or microwave radiation, as also described hereinabove,
depending on the materials to be cured. The application of
radiation (or irradiation) is effected by a suitable radiation
source. For example, an ultraviolet or visible or infrared or Xenon
lamp can be employed, as described herein.
A curable material or system that undergoes curing upon exposure to
radiation is referred to herein interchangeably as
"photopolymerizable" or "photoactivatable" or "photocurable".
When the curing energy comprises heat, the curing is also referred
to herein and in the art as "thermal curing" and comprises
application of thermal energy. Applying thermal energy can be
effected, for example, by heating a receiving medium onto which the
layers are dispensed or a chamber hosting the receiving medium, as
described herein. In some embodiments, the heating is effected
using a resistive heater.
In some embodiments, the heating is effected by irradiating the
dispensed layers by heat-inducing radiation. Such irradiation can
be effected, for example, by means of an IR lamp or Xenon lamp,
operated to emit radiation onto the deposited layer.
In some embodiments, heating is effected by infrared radiation
applied by a ceramic lamp, for example, a ceramic lamp that
produces infrared radiation of from about 3 .mu.m to about 6 .mu.m
or from about 3 .mu.m to about 4 .mu.m, e.g., about 3.5 .mu.m.
In some embodiments, the heat-inducing radiation is selected to
emit radiation at a wavelength that results in efficient absorption
of the heat energy by a selected ROMP monomer or mixture of
monomers, so as to effect efficient application of heat energy
(efficient heating or thermal curing).
A curable material or system that undergoes curing upon exposure to
heat is referred to herein as "thermally-curable" or
"thermally-activatable" or "thermally-polymerizable".
In some of any of the embodiments described herein, the method
further comprises exposing the cured modeling material
formulation(s) either before or after removal of a support material
formulation, if such has been included in the building material, to
a post-treatment condition. The post-treatment condition, which is
also referred to herein as post-curing treatment, is typically
aimed at further hardening the cured modeling formulation(s) and/or
at preventing its oxidation. In some embodiments, the post-curing
treatment hardens a partially-cured formulation to thereby obtain a
completely cured formulation.
In some embodiments, the post-curing treatment is effected by
exposure to heat or radiation, preferably at a reduced pressure
(vacuum), and optionally at atmospheric pressure under inert
atmosphere, as described in any of the respective embodiments
herein. In some embodiments, when the condition is heat, the
post-curing treatment can be effected for a time period that ranges
from a few minutes (e.g., 10 minutes) to a few hours (e.g., 1-24
hours). In some embodiments, the post-curing treatment is effected
for 2 hours. In some embodiments, the post-curing treatment
comprises heat, and heating is effected at a temperature that
ranges from about 50.degree. C. to about 250.degree. C., or from
about 50.degree. C. to about 200.degree. C., or from about
100.degree. C. to about 200.degree. C., or, for example, at
150.degree. C., and at a reduced pressure.
An inert atmosphere can be, for example, nitrogen and/or argon
atmosphere.
Reduced pressure can be, for example, lower than 200 mmHg, lower
than 100 mmHg, or lower than 50 mmHg, for example, about 20 mmHg,
although any other value is contemplated.
Alternatively, or in addition, the post-curing treatment comprises
applying to a surface of (or coating) the model object, or to a
part of the surface, a material or a composition that features
anti-oxidation activity, to thereby reduce or prevent oxidation of
the model object (or a part thereof) when exposed to ambient
environment. In some of these embodiments, the material or
composition is such that form a thin, preferably, but not
necessarily transparent, layer on the surface of the model object
or a part thereof. Any material or composition that feature
anti-oxidation activity and which can be readily applied to the
model object as described herein is contemplated. An exemplary such
composition is an acrylic paint, that is, a formulation that forms
an acrylic paint once deposited on a surface of the object.
Applying a material or composition featuring an anti-oxidation
activity and exposing to heat or radiation, within a post-curing
treatment as described herein, when used together, can be effected
sequentially or simultaneously. For example, a formulation forming
an acrylic paint can be applied to the surface of the model object,
and exposure to heat and/or radiation can be applied thereafter, to
thereby effect both formation of a layer of the acrylic paint and
further hardening of the cured modeling formulation.
In some of any of the embodiments described herein, at least one of
the modeling material formulations as described herein comprises a
monomer that is polymerizable by ring opening metathesis
polymerization (ROMP). Such a monomer is also referred to herein
interchangeably as a ROMP monomer, a ROMP-polymerizable monomer, a
ROMP curable monomer, a ROMP component, a ROMP active component,
and similar diversions. In some embodiments, one or more of the
modeling material formulations in the (uncured) building material
comprises a catalyst for initiating a ROMP reaction of the monomer,
as described in further detail hereinunder.
In some of any of the embodiments described herein, the ROMP
monomer is an unsaturated cyclic monomer, preferably a strained
unsaturated cyclic olefin, as described in further detail
hereinunder.
In some of any of the embodiments described herein, exposing the
modeling material formulation to a condition that induces curing
comprises exposing the dispensed modeling material formulation(s)
to a condition for inducing initiation of ROMP of the monomer by
the catalyst, as described in further detail hereinunder. Any of
the conditions for effecting curing as described hereinabove are
contemplated, depending on the materials selected for the ROMP
system.
Herein throughout, a condition for inducing initiation of ROMP of
the monomer by the catalyst is also referred to herein
interchangeably as "a ROMP inducing condition" or simply as
"inducing condition", and describes a condition to which a modeling
material formulation is exposed so as to effect ROMP of the ROMP
monomer (e.g., to effect initiation of ROMP of the ROMP monomer by
the catalyst).
A ROMP System:
Herein, a "ROMP system" describes a set of materials and optionally
conditions for effecting polymerization, via a ROMP reaction, of an
unsaturated cyclic ROMP monomer (or a mixture of ROMP monomers).
The materials included in a ROMP system are also referred to herein
as "ROMP components" or "ROMP active components".
A ROMP system requires at least a ROMP monomer and a catalyst for
initiating the ROMP reaction. The catalyst is also referred to
herein throughout as a "ROMP catalyst" or a "ROMP catalyst
system".
ROMP catalysts can be divided into active catalysts and latent
catalysts.
By "active catalyst" it is meant herein a catalyst which is active
towards initiation of ROMP of the monomer immediately once it
contacts the monomer, without a need to apply an external stimulus
such as, for example, heat, radiation, or chemical additives.
By "active towards initiation of ROMP" of the monomer it is meant
that in the presence of the catalyst, at least 50% or at least 60%
or at least 70% or at least 80% of the monomer polymerizes via ROMP
mechanism to provide a respective polymer.
An active catalyst is a ROMP catalyst that initiates ROMP of a
monomer when in contact with the ROMP monomer, without requiring a
stimulus. ROMP active catalysts are typically active at room
temperature.
By "latent catalyst" it is meant herein a catalyst which is
activatable only upon exposure to a condition. In such cases, the
catalyst is inactive towards initiation of ROMP of the monomer when
the ROMP system is not exposed to the condition that activates the
catalyst, namely, prior to exposure to a ROMP inducing
condition.
By "inactive towards initiation of ROMP" of the monomer it is meant
that in the presence of the catalyst, no more than 40% or no more
than 30% or no more than 20% or no more than 10% or no more than 5%
of the monomer polymerizes via ROMP mechanism to provide a
respective polymer.
A latent catalyst is a ROMP catalyst that initiates ROMP of a
monomer when in contact with the ROMP monomer, upon exposure to an
external stimulus, typically heat or radiation, or a chemical
stimulus. A latent catalyst is inactive in initiating ROMP of a
monomer in the absence of a suitable stimulus.
A latent catalyst typically includes a chelating (e.g., donor)
ligand which "blocks" a coordinative site of the metal and thus
renders the catalyst inactive. Activating the catalyst is effected
by dissociating the chelating ligand from the metal center, to
thereby render it active towards metathesis.
Latent catalysts can be thermally-activatable catalysts, which are
converted into active catalysts upon exposure to heat;
photo-activatable catalysts, which are converted into active
catalysts upon exposure to radiation; or chemically-activatable,
which are converted into active catalysts upon chemical activation
by another chemical entity, known as an activator.
By "chemically activating" it is meant that the activation of a
catalyst is made by an addition of a chemical entity (a chemical
additive), e.g., a chemical compound or a chemical species such as
an ion.
In such cases, the ROMP catalyst is inactive towards initiation of
ROMP of the monomer, as defined herein, in the absence of the
activator (when it is not contacted with the activator). A ROMP
catalyst that is activatable in the presence of an activator is
referred to herein also as a "pre-catalyst", and the activator is
referred to herein as a "co-catalyst". A combination of
pre-catalyst and an activator is also referred to herein and in the
art as a catalyst system, and herein also as a ROMP catalyst
system.
A pre-catalyst is typically inactive towards initiation of ROMP of
the monomer, as defined herein, in the absence of a respective
activator.
In such cases, a condition for initiating ROMP of a monomer
requires a contact between the catalyst and the activator and the
catalyst and the ROMP monomer.
A ROMP system in theses embodiments comprises, or consists of, a
ROMP monomer, a ROMP catalyst and an activator, for chemically
activating the ROMP catalyst.
The ROMP system can comprise an activator that is active towards
chemically activating the pre-catalyst once it contacts the
pre-catalyst, to thereby generate an active catalyst.
Alternatively, the activator can be an activatable activator, which
is rendered active towards chemically activating the catalyst when
exposed to a certain condition. In such cases, the activator is
incapable of chemically activating the catalyst unless it is
activated (by exposure to the condition). Such activators are also
referred to herein as "latent activators".
A latent activator is incapable of activating a catalyst for
initiating ROMP of the monomer, and can be converted to an active
activator when exposed to an activating condition (which can be the
ROMP inducing condition as described herein).
By "inactive towards chemically activating the catalyst" it is
meant that no chemical reaction between the activator and the
catalyst occurs, such that in the ROMP system containing the ROMP
monomer, a ROMP catalyst which is chemically activatable by the
activator, and the latent activator, no more than 40% or no more
than 30% or no more than 20% or no more than 10% or no more than 5%
of the monomer polymerizes via ROMP mechanism to provide a
respective polymer.
By "active towards chemically activating the catalyst" it is meant
that in a ROMP system containing the ROMP monomer, a ROMP catalyst
which is chemically activatable by the activator, and the
activator, at least 20% or at least 30% or at least 40% or at least
50% or at least 60% or at least 70% of the ROMP monomer polymerizes
via ROMP mechanism to provide a respective polymer.
Latent activators can be thermally-activatable activators, which
are converted into active activators upon exposure to heat (that
is, a condition for inducing initiation of ROMP comprises heat or
heating a ROMP system, optionally in addition to contacting an
activator and a catalyst and a ROMP monomer).
Latent activators as described herein can be photo-activatable
catalysts, which are converted into active activators upon exposure
to radiation (that is, a condition for inducing initiation of ROMP
comprises exposure to radiation or application of radiation to the
ROMP system, optionally in addition to contacting an activator and
a catalyst and a catalyst and a ROMP monomer). The radiation can
be, for example, an electromagnetic radiation (e.g., UV or visible
or IR light), or ultrasound radiation, and can be applied by a
suitable source of the radiation.
In some of any of the embodiments described herein, a ROMP system
can further comprise a ROMP inhibitor.
A "ROMP inhibitor" as used herein refers to a material that slows
down a ROMP reaction initiated by a catalyst. ROMP inhibitors can
be used with active catalysts, latent catalysts and pre-catalysts,
as described herein. In some embodiments, a ROMP inhibitor inhibits
a ROMP reaction initiated in the presence of an active catalyst, or
once a latent catalyst or pre-catalyst is converted to an active
catalyst, by interfering with the chemical reactions that activate
a latent catalyst or a pre-catalyst.
It is to be noted that a ROMP system as described herein refers to
the active components and/or conditions that together lead to ROMP
polymerization of a ROMP monomer. A formulation that comprises a
ROMP system can further comprise other components which can
participate in polymerization or curing reactions (e.g., curable
materials or systems), and/or form a part of the final polymeric
material, as described in further detail hereinbelow.
In some of any of the embodiments described herein, a ROMP system
comprises a ROMP monomer, a ROMP pre-catalyst and a ROMP activator,
and optionally a ROMP inhibitor.
In some of any of the embodiments described herein the ROMP
pre-catalyst is chemically-activatable by the activator, and in
some embodiments, the ROMP pre-catalyst is an acid-activatable
pre-catalyst.
In some of any of the embodiments described herein, the activator
is active towards chemically activating the pre-catalyst (namely,
it is an active activator), to thereby generate an active
catalyst.
In some of any of the embodiments described herein, the
pre-catalyst is an acid-activatable pre-catalyst and the activator
is an acid and/or an acid generator, as described herein.
Herein throughout, whenever a ROMP monomer is indicated, it is to
be understood as encompassing one or more (e.g., a mixture of two,
three or more) ROMP monomer(s); whenever a ROMP pre-catalyst is
indicated, it is to be understood as encompassing one or more
(e.g., a mixture of two, three or more) pre-catalyst(s); whenever a
ROMP activator is indicated, it is to be understood as encompassing
one or more (e.g., a mixture of two, three or more) ROMP
activator(s); and whenever a ROMP inhibitor is indicated, it is to
be understood as encompassing one or more (e.g., a mixture of two,
three or more) ROMP inhibitor(s).
Similarly, whenever reference to any other agent or moiety is made
herein throughout, it is to be understood as encompassing one or
more (e.g., a mixture of two, three or more) agent(s) or
moiety/moieties.
ROMP Monomers:
A ROMP monomer as described herein describes any material that
undergoes ROMP in the presence of a ROMP catalyst or ROMP catalyst
system.
Typically ROMP monomers are unsaturated cyclic compounds (cyclic
olefins), and preferably strained unsaturated cyclic compounds
(strained cyclic olefins).
Any compound that can undergo ROMP is encompassed by the present
embodiments.
The phrase "ROMP monomer" as used herein encompasses one ROMP
monomer or a combination of ROMP monomers, and also encompasses a
mixture of a ROMP monomer with another cyclic olefin that can react
with a ROMP monomer during ROMP of the ROMP monomer, if included in
the same reaction mixture. Such cyclic olefins can be recognized by
those skilled in the art.
Exemplary ROMP monomers include, but are not limited to
dicyclopentadiene (DCPD), cyclopentadiene trimer, tetramer,
pentamer, etc., norbornene, cyclooctene, cyclooctadiene,
cyclobutene, cyclopropene and substituted derivatives thereof, for
example, substituted norbornenes such as carboxylated norbornenes,
butyl norbornene, hexyl norbornene, octyl norbornene.
Any cyclic olefin (unsaturated cyclic compounds) suitable for the
metathesis reactions disclosed herein may be used.
Herein, the phrases "cyclic olefin" and "unsaturated cyclic
compound" are used interchangeably encompasses compounds comprising
one, two, three or more non-aromatic rings (fused and/or unfused
rings) which comprise at least one pair of adjacent carbon atoms in
the ring which are bound to one another by an unsaturated bond. The
ring may optionally be substituted or unsubstituted, and the cyclic
olefin may optionally comprise one unsaturated bond
("monounsaturated"), two unsaturated bonds ("di-unsaturated"),
three unsaturated bond ("tri-unsaturated"), or more than three
unsaturated bonds. When substituted, any number of substituents may
be present (optionally from 1 to 5, and optionally 2, 3, 4 or 5
substituents), and the substituent(s) may optionally be any
substituent describes herein as being optionally attached to an
alkyl or alkenyl.
Examples of cyclic olefins include, without limitation,
cyclooctene, cyclododecene, and
(c,t,t)-1,5,9-cyclododecatriene.
Examples of cyclic olefins with more than one ring include, without
limitation, norbornene, dicyclopentadiene, tricyclopentadiene, and
5-ethylidene-2-norbornene.
The cyclic olefin may be a strained or unstrained cyclic olefin,
provided the cyclic olefin is able to participate in a ROMP
reaction either individually or as part of a ROMP cyclic olefin
composition. While certain unstrained cyclic olefins such as
cyclohexene are generally understood to not undergo ROMP reactions
by themselves, under appropriate circumstances, such unstrained
cyclic olefins may nonetheless be ROMP active. For example, when
present as a co-monomer in a ROMP composition, unstrained cyclic
olefins may be ROMP active. Accordingly, as used herein and as
would be appreciated by the skilled artisan, the term "unstrained
cyclic olefin" is intended to refer to those unstrained cyclic
olefins that may undergo a ROMP reaction under any conditions, or
in any ROMP composition, provided the unstrained cyclic olefin is
ROMP active.
In some embodiments of any one of the embodiments described herein,
the substituted or unsubstituted cyclic olefin comprises from 5 to
24 carbon atoms. In some such embodiments, the cyclic olefin is a
hydrocarbon devoid of heteroatoms. In alternative embodiments, the
cyclic olefin comprises one or more (e.g., from 2 to 12)
heteroatoms such as O, N, S, or P, for example, crown ether cyclic
olefins which include numerous O heteroatoms throughout the cycle,
are within the scope of the invention.
In some embodiments of any one of the embodiments described herein
relating to a cyclic olefin comprising from 5 to 24 carbon atoms,
the cyclic olefin is mono-unsaturated, di-unsaturated, or
tri-unsaturated.
In some embodiments of any of the embodiments described herein, the
cyclic olefin has the general formula (A):
##STR00005## wherein:
R.sup.A1 and R.sup.A2 are each independently hydrogen, alkyl,
cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic,
halo, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,
thioaryloxy, sulfinyl, sulfonyl, sulfonate, nitrile, nitro, azide,
phosphonyl, phosphinyl, oxo, carbonyl, thiocarbonyl, urea,
thiourea, carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl,
C-amido, N-amido, C-carboxy, O-carboxy, sulfonamido, and amino;
J is a saturated or unsaturated hydrocarbon, which may be
substituted or unsubstituted, and may optionally comprise one or
more heteroatoms between the carbon atoms thereof. Additionally,
two or more substituents attached to ring atoms within J may
optionally be linked to form a bicyclic or polycyclic olefin.
In some embodiments of any of the respective embodiments described
herein, the compound of formula (A) contains from 5 to 14 ring
atoms, optionally from 5 to 8 ring atoms, for a monocyclic olefin;
and, for bicyclic and polycyclic olefins, from 4 to 8 ring atoms in
each ring, optionally from 5 to 7 ring atoms in each ring.
In some embodiments of any of the embodiments described herein, the
cyclic olefin has the general formula (B):
##STR00006## wherein:
b is an integer in a range of 1 to 10, optionally 1 to 5;
R.sup.A1 and R.sup.A2 are as defined above for formula (A); and
R.sup.B1, R.sup.B2, R.sup.B3, R.sup.B4, R.sup.B5, and R.sup.B6 are
each independently hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl,
aryl, heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy,
thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl,
sulfonate, nitrile, nitro, azide, phosphonyl, phosphinyl, oxo,
carbonyl, thiocarbonyl, urea, thiourea, carbamyl, N-carbamyl,
O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, C-carboxy,
O-carboxy, sulfonamido, and amino, or alternatively, any of the
R.sup.B1, R.sup.B2, R.sup.B3, R.sup.B4, R.sup.B5, and R.sup.B6
moieties can be linked to any of the other R.sup.B1, R.sup.B2,
R.sup.B3, R.sup.B4, R.sup.B5, and R.sup.B6 moieties to provide a
substituted or unsubstituted 4- to 7-membered ring;
In some embodiments of any of the embodiments described herein, the
cyclic olefin is monocyclic.
In some embodiments of any of the embodiments described herein, the
cyclic olefin is monounsaturated, optionally being both monocyclic
and monounsaturated.
Examples of monounsaturated, monocyclic olefins encompassed by
formula (B) include, without limitation, cyclopentene, cyclohexene,
cycloheptene, cyclooctene, cyclononene, cyclodecene, cycloundecene,
cyclododecene, tricyclodecene, tetracyclodecene, octacyclodecene,
and cycloeicosene, and substituted versions thereof such as
methylcyclopentene (e.g., 1-methylcyclopentene,
4-methylcyclopentene), ethylcyclopentene (e.g.,
1-ethylcyclopentene), isopropylcyclohexene (e.g.,
1-isopropylcyclohexene), chloropentene (e.g., 1-chloropentene),
fluorocyclopentene (e.g. 1-fluorocyclopentene), methoxycyclopentene
(e.g., 4-methoxy-cyclopentene), ethoxycyclopentene (e.g.,
4-ethoxy-cyclopentene), cyclopentene-thiol (e.g.,
cyclopent-3-ene-thiol), methylsulfanyl-cyclopentene (e.g.,
4-methylsulfanyl-cyclopentene), methylcyclohexene (e.g.,
3-methylcyclohexene), methylcyclooctene (e.g.,
1-methylcyclooctene), and dimethylcyclooctene (e.g.,
1,5-dimethylcyclooctene).
In some embodiments of any of the embodiments described herein, the
cyclic olefin is diunsaturated, optionally being both monocyclic
and diunsaturated.
In some embodiments, the cyclic olefin has the general formula
(C):
##STR00007## wherein
c and d are each independently integers in the range of from 1 to
8, optionally from 2 to 4, and optionally 2 (such that the cyclic
olefin is a cyclooctadiene);
R.sup.A1 and R.sup.A2 are as defined above for formula (A); and
R.sup.C1, R.sup.C2, R.sup.C3, R.sup.C4, R.sup.C5, and R.sup.C6 are
each independently defined as for R.sup.B1-R.sup.B6.
In some embodiments, R.sup.c3 and R.sup.C4 are substituents (i.e.,
not hydrogen), in which case at least one of the olefinic moieties
is tetrasubstituted.
Examples of diunsaturated, monocyclic olefins include, without
limitation, 1,3-cyclopentadiene, 1,3-cyclohexadiene,
1,4-cyclohexadiene, heptadiene (e.g., 1,3-cycloheptadiene),
octadiene (e.g., 1,5-cyclooctadiene, 1,3-cyclooctadiene), and
substituted versions thereof (e.g.,
5-ethyl-1,3-cyclohexadiene).
In some embodiments of any of the embodiments described herein, the
cyclic olefin comprises more than two (optionally three)
unsaturated bonds. In some embodiments, such compounds are
analogous to the diene structure of formula (C), comprising at
least one methylene linkage (analogous to the number of methylene
linkages indicated by the variables c and d in formula (C)) between
any two olefinic segments.
In some embodiments of any of the embodiments described herein, the
cyclic olefin is polycyclic.
Herein, the term "polycyclic" refers to a structure comprising two
or more fused rings.
In some embodiments of any of the embodiments described herein, the
cyclic olefin is a polycyclic olefin having the general formula
(D):
##STR00008## wherein:
R.sup.A1 and R.sup.A2 are each independently as defined above for
formula (A):
R.sup.D1, R.sup.D2, R.sup.D3 and R.sup.D4 are each independently as
defined for R.sup.B1-R.sup.B6;
e is an integer in the range of from 1 to 8, optionally from 2 to
4:
f is 1 or 2; and
T is a substituted or unsubstituted saturated or unsaturated
hydrocarbon of 1-4 carbon atoms in length (optionally 1 or 2 carbon
atoms in length, for example, substituted or unsubstituted methyl
or ethyl), O, S, N(R.sup.G1), P(R.sup.G1), P(.dbd.O)(R.sup.G1),
Si(R.sup.G1).sub.2, B(R.sup.G1), or As(R.sup.G1), wherein R.sup.G1
is alkyl, alkenyl, alkynyl, cycloalkyl, heteroalicyclic, aryl,
heteroaryl, alkoxy or aryloxy.
Cyclic olefins encompassed by formula (D) are examples of compounds
in the norbornene family.
As used herein, the term "norbornene" refers to any compound that
includes at least one substituted or unsubstituted
bicyclo[2.2.1]hept-2-ene moiety or dehydrogenated derivative
thereof, including without limitation, bicyclo[2.2.1]hept-2-ene
(referred to in the art as "norbornene") and substituted versions
thereof, norbornadiene, (bicyclo[2.2.1]hepta-2,5-diene) and
substituted versions thereof, and polycyclic norbornenes, and
substituted versions thereof.
In some embodiments, the cyclic olefin is a polycyclic norbornene
having the general formula (E):
##STR00009## wherein:
R.sup.A1 and R.sup.A2 are each independently as defined above for
formula (A);
T is as defined above for formula (D);
R.sup.E1, R.sup.E2, R.sup.E3, R.sup.E4, R.sup.E5, R.sup.E6,
R.sup.E7, and R.sup.E8 are each independently as defined for
R.sup.B1-R.sup.B6; and
"a" represents a saturated bond or unsaturated double bond, wherein
when "a" is an unsaturated double bond, one of R.sup.E5, R.sup.E6
and one of R.sup.E7, R.sup.E8 is absent;
f is 1 or 2; and
g is an integer from 0 to 5.
In some embodiments, the cyclic olefin has the general formula
(F):
##STR00010## wherein:
R.sup.F1, R.sup.F2, R.sup.F3 and R.sup.F4 defined above for
R.sup.E4, R.sup.E5, R.sup.E6, R.sup.E7, and R.sup.E8 respectively;
and
a and g are as defined in formula (E) hereinabove.
Examples of bicyclic and polycyclic olefins include, without
limitation, dicyclopentadiene (DCPD); trimer and higher order
oligomers of cyclopentadiene (e.g. cyclopentadiene tetramer,
cyclopentadiene pentamer); ethylidenenorbornene; dicyclohexadiene;
norbornene; 5-methyl-2-norbornene; 5-ethyl-2-norbornene:
5-isobutyl-2-norbornene; 5,6-dimethyl-2-norbornene;
5-phenylnorbornene; 5-benzylnorbornene; 5-acetylnorbornene:
5-methoxycarbonylnorbornene; 5-ethyoxycarbonyl-1-norbornene;
5-methyl-5-methoxy-carbonylnorbornene; 5-cyanonorbornene;
5,5,6-trimethyl-2-norbornene; cyclo-hexenylnorbornene;
endo,exo-5,6-dimethoxynorbornene;
endo,endo-5,6-dimethoxynorbornene;
endo,exo-5,6-dimethoxycarbonylnorbornene;
endo,endo-5,6-dimethoxycarbonylnorbornene; 2,3-dimethoxynorbornene;
norbornadiene; tricycloundecene; tetracyclododecene;
8-methyltetracyclododecene; 8-ethyltetracyclododecene;
8-methoxycarbonyltetracyclododecene; 8-methyl-8-tetracyclododecene:
8-cyanotetracyclododecene; pentacyclopentadecene;
pentacyclohexadecene; and the like, and their structural isomers,
stereoisomers, and mixtures thereof.
Additional examples of bicyclic and polycyclic olefins include,
without limitation, C.sub.2-C.sub.12-alkyl-substituted and
C.sub.2-C.sub.12-alkenyl-substituted norbornenes, for example,
5-butyl-2-norbornene, 5-hexyl-2-norbornene, 5-octyl-2-norbornene,
5-decyl-2-norbornene, 5-dodecyl-2-norbornene, 5-vinyl-2-norbornene,
5-ethylidene-2-norbornene, 5-isopropenyl-2-norbornene,
5-propenyl-2-norbornene, and 5-butenyl-2-norbornene, and the
like.
In some embodiments of any of the embodiments described herein, the
cyclic olefin is dicyclopentadiene: tricyclopentadiene;
dicyclohexadiene; norbornene; 5-methyl-2-norbornene;
5-ethyl-2-norbornene; 5-isobutyl-2-norbornene;
5,6-dimethyl-2-norbornene; 5-phenylnorbornene: 5-benzylnorbornene:
5-acetylnorbornene: 5-methoxycarbonylnorbornene;
5-ethoxycarbonyl-1-norbornene;
5-methyl-5-methoxy-carbonylnorbornene; 5-cyanonorbornene;
5,5,6-trimethyl-2-norbornene; cyclo-hexenylnorbornene;
endo,exo-5,6-dimethoxynorbornene;
endo,endo-5,6-dimethoxynorbornene;
endo,exo-5-6-dimethoxycarbonylnorbornene:
endo,endo-5,6-dimethoxycarbonylnorbornene; 2,3-dimethoxynorbornene;
norbornadiene; tricycloundecene; tetracyclododecene;
8-methyltetracyclododecene; 8-ethyl-tetracyclododecene;
8-methoxycarbonyltetracyclododecene:
8-methyl-8-tetracyclo-dodecene; 8-cyanotetracyclododecene;
pentacyclopentadecene; pentacyclohexadecene; an oligomer of
cyclopentadiene (e.g., cyclopentadiene tetramer, cyclopentadiene
pentamer); and/or a C.sub.2-C.sub.12-alkyl-substituted norbornene
or C.sub.2-C.sub.12-alkenyl-substituted norbornene (e.g.,
5-butyl-2-norbornene; 5-hexyl-2-norbornene; 5-octyl-2-norbornene;
5-decyl-2-norbornene; 5-dodecyl-2-norbornene; 5-vinyl-2-norbornene;
5-ethylidene-2-norbornene; 5-isopropenyl-2-norbornene;
5-propenyl-2-norbornene; 5-butenyl-2-norbornene).
In some embodiments of any of the embodiments described herein, the
cyclic olefin is dicyclopentadiene, tricyclopentadiene, or higher
order oligomer of cyclopentadiene (e.g., cyclopentadiene tetramer,
cyclopentadiene pentamer), tetracyclododecene, norbornene, and/or a
C.sub.2-C.sub.12-alkyl-substituted norbornene or
C.sub.2-C.sub.12-alkenyl-substituted norbornene (e.g., according to
any of the respective embodiments described herein).
Additional examples for ROMP capable cyclic olefin monomers which
may be optionally used in embodiments of the invention include any
polycyclic compounds which are characterized by the presence of at
least two norbornene moieties in its structure, for example:
##STR00011##
In some embodiments of any of the embodiments described herein, the
cyclic olefin is characterized by the presence of at least three
rings.
In some embodiments of any of the embodiments described herein
relating to a norbornene-based monomer, a monocyclic olefin (e.g.,
cyclobutene, cyclopentene, cyclopentadiene, cyclooctene,
cyclododecene) is copolymerized with the norbornene-based
monomer.
Without being bound by any particular theory, it is believed that
polycyclic monomers with a rigid backbone, such as cyclopentadiene
trimer (TCPD or CPD trimer) will typically produce a cross-linked
polymer with very high Tg and heat deflection temperature (HDT),
but will also be more brittle and may have lower Impact
resistance.
In some embodiments of any of the embodiments described herein, a
polycyclic monomer with a rigid backbone (e.g., according to any of
the respective embodiments described herein) is formulated with one
or more softer additional monomers and/or cross linkers.
Examples of additional monomers include, without limitation,
monomers having the formula:
##STR00012##
wherein Rx and Ry are each independently hydrogen,
C.sub.1-C.sub.20-alkyl, cycloalkyl, heteroalicyclic, aryl,
polyethylene glycol, polypropylene glycol or benzyl.
Example of bifunctional cyclic olefins, which may also act as cross
linkers include, without limitation, compounds having any one of
the following formulas:
##STR00013##
wherein Rx and Ry are each independently hydrogen,
C.sub.1-C.sub.20-alkyl, cycloalkyl, heteroalicyclic, aryl,
polyethylene glycol, polypropylene glycol or benzyl; and
K.sub.1 and K.sub.2 are each independently
C.sub.1-C.sub.20-alkylene, cycloalkyl, heteroalicyclic, aryl,
polyethylene glycol, polypropylene glycol or benzyl.
Additional examples of bifunctional cyclic olefins include, without
limitation:
##STR00014##
The connection between an additional monomer and/or bifunctional
monomer (cross-linker) to a polycyclic (e.g., norbornene) monomer
may optionally be, without limitation, through a saturated or
unsaturated carbon-carbon bond, an ester bond, and ether bond, an
amine, or an amide bond.
Synthesis of norbornene derivatives described herein according to
any of the respective embodiments may optionally be performed by
Diels-Alder reaction of double bond with cyclopentadiene (CPD), as
depicted in Scheme 1 below:
Scheme 1
##STR00015##
Substituents of a polymerized cyclic olefin may optionally be in a
protected form in the monomer. For example, hydroxy groups, which
may interfere with metathesis catalysis, may be protected by being
in a form of any suitable protected group used in the art.
Acceptable protecting groups may be found, for example, in Greene
et al., Protective Groups in Organic Synthesis, 3rd Ed. (New York:
Wiley, 1999).
Table A below presents non-limiting examples of suitable ROMP
polymerizable monomers according to some embodiments of the present
invention.
In a preferred embodiment, the ROMP monomer is or comprises DCPD
due to its high reactivity, and the high thermal resistance and
toughness properties exhibited by a printed object made
therefrom.
In a preferred embodiment, the ROMP monomer is or comprises a CPD
trimer due to its suitable viscosity and the high thermal
resistance exhibited by a printed object made therefrom.
In a preferred embodiment, a ROMP monomer is or comprises a mixture
of DCPD and CPD trimer, for example, a mixture known in the art,
and also referred to herein as "RIM monomer". In some embodiments,
such a mixture comprises DCPD at a concentration ranging from about
70% to about 99%, or from 85% to about 95%, by weight, of the total
weight of a ROMP monomer, and a CPD trimer at a concentration
ranging from about 30% to about 1%, or from about 15% to about 5%,
respectively, by weight, of the total weight of a ROMP monomer.
In a commercially available "RIM monomer", a concentration of DCPD
is typically from about 90% to about 92%.
In some embodiments, a ROMP monomer is or comprises about 91% DCPD
and about 9% CPD trimer, as described herein.
TABLE-US-00001 TABLE A Tradename Structure Supplier DCPD
Dicyclopentadiene Telene SAS RIM monomer Cyclopentadiene trimer in
Telene SAS dicyclopentadiene Cyclopentadiene trimer Cyclopentadiene
trimer Zeon Cyclooctene Cyclooctene Sigma Aldrich Cyclooctadiene
Cyclooctadiene Sigma Aldrich Norbornene Norbornene Sigma Aldrich
ENB 5-Ethylidene-2-norbornene Sigma Aldrich cyclododecatriene
cyclododecatriene BASF
ROMP Catalysts and Catalyst Systems:
In some of any of the embodiments described herein, the ROMP
catalyst system comprises an acid-activatable ROMP pre-catalyst and
an activator that is active towards chemically activating the
pre-catalyst. In some embodiments, the activator is an acid, as
described herein, and in some embodiments, the activator is capable
of generating an acid.
ROMP catalysts typically include metal carbene organometallic
complexes, with the metal being typically, but not necessarily, a
transition metal such as ruthenium, molybdenum, osmium or
tungsten.
Ruthenium based ROMP catalysts are more stable on exposure to non
carbon-carbon double-bond functional groups, and to other
impurities like water and oxygen. These catalysts can typically be
used in low loading in the formulation (e.g., in a range of from
about 0.002% to about 0.05% by weight of the total weight of a
modeling material formulation containing same).
A ROMP pre-catalyst is a ROMP catalyst that initiates ROMP of a
monomer when in contact with the ROMP monomer, upon exposure to a
chemical stimulus, as described herein, typically a presence of an
acid or a proton, which converts the pre-catalyst to an active
catalyst (which induces ROMP of a ROMP monomer when in contact with
the ROMP monomer). A pre-catalyst is inactive in initiating ROMP of
a monomer in the absence of the chemical stimulus.
A pre-catalyst typically includes a chelating (e.g., donor) ligand
which "blocks" a coordinative site of the metal and thus renders
the catalyst inactive. Activating the catalyst is effected by
dissociating the chelating ligand from the metal center, to thereby
render it active towards metathesis.
In a pre-catalyst, dissociating the chelating ligand requires a
chemical stimulus, typically a presence of an acid. The agent that
exerts a chemical stimulus that activates the catalyst is referred
to herein as an activator or a co-catalyst.
A ROMP pre-catalyst and a suitable activator form together a
catalyst system.
In some of any of the embodiments described herein, the
pre-catalyst is an acid-activatable pre-catalyst, particularly a
Ruthenium (Ru) based acid-activatable pre-catalyst.
In some of any of the embodiments described herein, the Ru-based
catalyst bears one or more bidentate Schiff base ligands.
Exemplary such Schiff-base ligands are described, for example, in
EP Patent No. 1468004, which is incorporated by reference as if
fully set forth herein.
In some embodiments, the bidentate Schiff base ligand is derived
from a salicyldiamine derivative, as described, for example, in EP
Patent Application Nos. 8290747 and 8290748, and in US Patent
Application Publication No. 2012/0271019, which are incorporated by
reference as if fully set forth herein.
In some embodiments, the pre-catalyst is represented by the general
Formula I:
##STR00016##
wherein:
L.sub.1 and L.sub.2 are each independently common ligands of
ruthenium-based catalysts for ROMP, including, for example, carbene
ligands and halogen ligands, as described in further detail
hereinbelow, or, alternatively, one of L.sub.1 and L.sub.2 is a
bidentate Schiff base ligand, as described herein:
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each
independently selected from the group consisting of hydrogen,
halogen, alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl,
heteroaryl, alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl,
alkylamino, alkylthio, aminosulfonyl, monoalkylaminosulfonyl,
dialkylaminosulfonyl, alkylsulfonyl, nitrile, nitro, alkylsulfinyl,
trihaloalkyl, perfluoroalkyl, carboxylic acid, ketone, aldehyde,
nitrate, cyano, isocyanate, thioisocyanate, cyanato, thiocyanato,
hydroxyl, ester, ether, thioether, amine, alkylamine, imine, amide,
halogen-substituted amide, trifluoroamide, sulfide, disulfide,
sulfonate, carbamate, silane, siloxane, phosphine, phosphate,
borate, or -A-Fn, wherein "A" is absent or is a divalent
hydrocarbon moiety selected from alkylene and arylalkylene, wherein
the alkyl portion of the alkylene and arylalkylene groups can be
linear or branched, saturated or unsaturated, cyclic or acyclic,
and substituted or unsubstituted, wherein the aryl portion of the
arylalkylene can be substituted or unsubstituted, and wherein
hetero atoms and/or functional groups may be present in either the
aryl or the alkyl portions of the alkylene and arylalkylene groups,
and Fn is any one or more of the R.sub.1, R.sub.2, R.sub.3,
R.sub.4, R.sub.5 and R.sub.6 which may be linked together to form a
cyclic group;
R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are each independently
selected from the group consisting of hydrogen, halogen, alkyl,
alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl, heteroaryl,
alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl, alkylamino,
alkylthio, aminosulfonyl, monoalkylaminosulfonyl,
dialkylaminosulfonyl, alkylsulfonyl, nitrile, nitro, alkylsulfinyl,
trihaloalkyl, perfluoroalkyl, carboxylic acid, ketone, aldehyde,
nitrate, cyano, isocyanate, thioisocyanate, cyanato, thiocyanato,
hydroxyl, ester, ether, thioether, amine, alkylamine, imine, amide,
halogen-substituted amide, trifluoroamide, sulfide, disulfide,
sulfonate, carbamate, silane, siloxane, phosphine, phosphate, and
borate, or, alternatively, two of R.sub.7-R.sub.10 form together a
cyclic ring.
Herein, a "cyclic ring" can be an alicyclic (e.g., cycloalkyl),
heteroalicyclic, aromatic (aryl) or heteroaromatic (heteroaryl)
ring, as these terms are defined herein.
In some of any of the embodiments of Formula I herein, R.sub.1,
R.sub.2, R.sub.3 and R.sub.4 form together a cyclic ring, and in
some embodiments, the cyclic ring is an aromatic ring (an aryl). In
some embodiments, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 form
together a phenyl, which can be substituted or unsubstituted. In
some embodiments, the phenyl is unsubstituted.
In some of any of the embodiments of Formula I herein, R.sub.5 is
an aryl (e.g., phenyl, for example, an unsubstituted phenyl).
In some of any of the embodiments of Formula I herein. R.sub.10 is
an aryl, and in some embodiments, it is phenyl which can be
substituted or unsubstituted. In some embodiments, the phenyl is
substituted, and in some embodiments, it is substituted by an alkyl
(e.g., linear or branched, primary, secondary or tertiary
alkyl).
In some of any of the embodiments of Formula I herein, two of
R.sub.7, R.sub.8 and R.sub.9 form a cyclic ring, and in some of
these embodiments, the cyclic ring is an aromatic ring (e.g., an
aryl such as phenyl). In some of these embodiments, the aromatic
ring is phenyl, which can be substituted or unsubstituted. In some
embodiments, the phenyl is substituted, for example, by alkoxy.
In some of any of the embodiments herein, at least one of L.sub.1
and L.sub.2 is a nucleophilic carbene ligand, and in some
embodiments, the carbene ligand is represented by the Formula:
##STR00017##
wherein Ra and Rb are each independently aryl, cycloalkyl or aryl
(e.g., phenyl).
In some embodiments, each of Ra and Rb is an aryl, and in some
embodiments, each is phenyl. In some embodiments, the phenyl is
substituted, and in some embodiments. Ra and Rb are both mesitylene
(2,4,6-trimethylphenyl).
Other nucleophilic carbene ligands are contemplated, for example,
any of those described in U.S. Patent Application having
Publication No. 2012/0271019.
In some embodiments, one of L.sub.1 and L.sub.2 is halogen.
In some embodiments. L.sub.1 is a nucleophilic carbene ligand and
L.sub.2 is halogen. In these embodiments, the Ru-based pre-catalyst
bears one bidentate Schiff base ligand.
Exemplary such pre-catalysts can be represented by Formula II:
##STR00018##
wherein Rc and Rd each independently represent one or more
substituents which are each independently as defined herein for
R.sub.7-R.sub.9.
In some embodiments, Rc and Rd can each be independently alkyl,
alkenyl, alkynyl, alkoxy, aryl, aryloxy, carboxylate, thioalkoxy
and thioaryloxy.
An exemplary such catalyst is VC 834 (see. Table B).
In some embodiments, one of L.sub.1 and L.sub.2 is a bidentate
Schiff base ligand such that the pre-catalyst bears two bidentate
Schiff base ligands.
The two Schiff-base ligands can be the same or different.
In some embodiments, the second Schiff base ligand is derived from
a salicyldiamine derivative, as described, for example, in EP
Patent Application Nos. 8290747 and 8290748, and in US Patent
Application Publication No. 2012/0271019, which are incorporated by
reference as if fully set forth herein.
In some embodiments, the pre-catalyst is represented by the general
Formula I as described herein, wherein L.sub.1 is a nucleophilic
carbene ligand as defined herein and L.sub.2 is a Schiff base
ligand as defined herein.
In some embodiments, the pre-catalyst is represented by the Formula
III:
##STR00019##
wherein Rc and Rd are as defined herein, and Re and Rf are as
defined herein for Rc and Rd.
Exemplary such pre-catalysts, marketed by Telene SAS, are presented
in Table B.
TABLE-US-00002 TABLE B Structure (Tradename) ##STR00020## (VC1161)
##STR00021## (VC843) ##STR00022## ##STR00023## ##STR00024##
##STR00025##
In some of any of the embodiments described herein, the
pre-catalyst comprises at least two acid-activatable Ru-based
pre-catalysts.
In some of any of the embodiments described herein, the
pre-catalyst comprises at least two catalysts represented by the
Formula I as described herein in any of the respective
embodiments.
In some of any of the embodiments described herein, the
pre-catalyst comprises at least two acid-activatable Ru-based
pre-catalysts, wherein one of the pre-catalysts comprises one
bidentate Schiff-base ligand, as described herein, and one of the
pre-catalysts comprises two bidentate Schiff base ligands, as
described herein.
In some of any the embodiments described herein, the pre-catalyst
comprises at least two catalysts represented by the Formula I as
described herein in any of the respective embodiments, wherein for
one of the pre-catalysts L.sub.1 and L.sub.2 are independently
selected from a nucleophilic carbene ligand and halogen, and in
another pre-catalyst, one of L.sub.1 and L.sub.2 is a bidentate
Schiff base ligand as described herein.
In some embodiments, the pre-catalyst comprises a mixture of a
pre-catalyst represented by Formula II and a pre-catalyst
represented by Formula III.
Whenever a mixture of pre-catalysts is used as a pre-catalyst of
the present embodiments, a ratio between the pre-catalysts can
range from 90:10 to 10:90, or from 80:20 to 20:80, or from 73:30 to
30:70, or from 60:40 to 40:60, or is 50:50.
In some embodiments, a ratio between a pre-catalyst having one
bidentate Schiff base ligand and a pre-catalyst having two
bidentate Schiff base ligands (e.g., a pre-catalyst of Formula I in
which L.sub.1 and L.sub.2 are independently selected from a
nucleophilic carbene ligand and halogen, and a pre-catalyst of
Formula I in which one of L.sub.1 and L.sub.2 is a bidentate Schiff
base ligand as described herein; or pre-catalyst of Formula II and
a pre-catalyst of Formula III) ranges from 90:10 to 10:90, or from
80:20 to 20:80, or from 73:30 to 30:70, or from 60:40 to 40:60, or
is 50:50. In some of these embodiments, the ratio is 60:40.
In some of any of the embodiments described herein the catalyst
system used in the modeling material formulations described herein
comprises a mixture of a pre-catalyst of Formula II and a
pre-catalyst of Formula III, and in some embodiments, a mixture of
VC834 and VC1161, and in some of these embodiments, the ratio
between the pre-catalysts ranges from 90:10 to 10:90, or from 80:20
to 20:80, or from 73:30 to 30:70, or from 60:40 to 40:60, or is
50:50. In some of these embodiments, the ratio is 60:40
(VC834:VC5761). In some of these embodiments, the ratio is 40:60
(VC834:VC1161). In some of these embodiments, the ratio is 20:80
(VC834:VC1161).
Activators suitable for use with the Ru-based acid-activatable
pre-catalysts described herein include acids, such as, for example,
inorganic acids (e.g., HCl), organic acids such as, for example,
acetic acid, propionic acid, and Lewis-Bronsted acids such as, for
example, organochlorosilanes.
In some embodiments, the activator is an organochlorosilane, which
can be selected from those represented by the Formula:
(R).sub.nSi(Cl).sub.4-n,
wherein R can be hydrogen, alkyl, cycloalkyl or aryl, and includes
at least one of alkyl, cycloalkyl or aryl, each of the alkyl,
cycloalkyl and aryl being optionally substituted, and n is 1, 2, or
3.
When n is 2 or 3, the "R" groups can be the same or different.
In some of any of the embodiments described herein, the alkyl can
be linear or branched, preferably linear, substituted or
unsubstituted, as defined herein, and can be of 1 to 30 carbon
atoms, or from 1 to 20 carbon atoms.
In some embodiments, n is 1 and R is an aryl, for example,
phenyl.
In some embodiments, n is 1 and R is an alkyl, for example, an
unsubstituted alkyl. In some of these embodiments, n is 1 and R is
an alkyl of 2 or more, preferably 3 or more, preferably 4 or more
carbon atoms in length. In some of these embodiments, the alkyl is
of from 4 to 30, or from 4 to 20, or from 6 to 20, or from 8 to 20
carbon atoms in length. In a preferred embodiment, n is 1 and R is
an unsubstituted alkyl of 10 carbon atoms in length.
The alkyl is preferably linear but can also be a branched
alkyl.
Optionally, n is 1 and R is a substituted alkyl as described
herein, of, for example, from 4 to 30, or from 4 to 20, or from 6
to 20, or from 8 to 20 carbon atoms in length.
In some of these embodiments, the alkyl is substituted by one or
more halo atoms, for example, chloro or fluoro atoms. In some of
these embodiments, the alkyl is fully substituted (all hydrogen
atoms are substituted) by halo atoms, for example, fluoro
atoms.
In some embodiments, n is 2, and each of the "R" groups is
independently an aryl, for example, phenyl. In some embodiments,
the aryl (e.g., phenyl) is unsubstituted.
In some embodiments, n is 2, one of the "R" groups is an aryl, for
example, phenyl, and the other "R" group is hydrogen or alkyl. In
some embodiments, the aryl (e.g., phenyl) is unsubstituted. In some
embodiments the alkyl, if present, is a short alkyl, of 1 to 4
carbon atoms in length (e.g., methyl). In some embodiments, the
alkyl is unsubstituted.
In some embodiments, n is 3, and at least one of the three "R"
groups is aryl and alkyl. In some of these embodiments, one of the
R groups is aryl (e.g., phenyl) and the to other two R groups are
independently an alkyl (e.g., methyl). The alkyl is preferably a
short alkyl of 1 to 4 carbon atoms in length. In some of these
embodiments, one of the R groups is aryl (e.g., phenyl), and the
other two R groups are hydrogen. In some of any of these
embodiments, the aryl and/or the alkyl is unsubstituted. In some of
any of these embodiments, the alkyl is a linear alkyl.
In some embodiments, n is 3 and each of the three "R" groups is
independently an alkyl.
In some of these embodiments, each of the R groups is an alkyl of 1
to 4 carbon atoms in length. In some of these embodiments, one or
more of the R groups is an unsubstituted methyl. In some of these
embodiments, each of the three R groups is an unsubstituted methyl.
In some of these embodiments, two of the R groups are each an
unsubstituted methyl, and one of the R groups is a substituted
methyl. The methyl can be substituted by, for example, one or more
halo atoms, for example, one or two chloro or fluoro atoms.
In some embodiments, n is 3, two of the R groups are each a methyl
(e.g. unsubstituted methyl), and one of the R groups is an alkyl of
at least 4 carbon atoms in length. In some of these embodiments,
the alkyl is of from 4 to 30, or from 4 to 20, or from 6 to 20, or
from 8 to 20 carbon atoms in length.
The alkyl is preferably linear but can also be a branched
alkyl.
Optionally, n is 3, two of the R groups are each a methyl (e.g.,
unsubstituted methyl), and one of the R groups is a substituted
alkyl as described herein, of, for example, from 4 to 30, or from 4
to 20, or from 6 to 20, or from 8 to 20 carbon atoms in length. In
some of these embodiments, the alkyl is substituted by one or more
halo atoms, for example, chloro or fluoro atoms. In some of this
embodiments, the alkyl is fully substituted (all hydrogen atoms are
substituted) by halo atoms, for example, fluoro atoms.
Exemplary activators suitable for use in combination with the
pre-catalysts described herein are presented in Table C below.
TABLE-US-00003 TABLE C Tradename Structure Supplier
Trichloro(phenyl)silane ##STR00026## Sigma Aldrich Acid activator
HCl Sigma Acid Aldrich activator Chlorophenylsilane ##STR00027##
Sigma Aldrich Acid activator Dichloro(phenyl)silane ##STR00028##
Sigma Aldrich Acid activator Dichloromethyl(phenyl)silane
##STR00029## Sigma Aldrich Acid activator ChloroDimethyl Phenyl
Silane ##STR00030## Sigma Aldrich Acid activator
ChloroTrimethylSilane ##STR00031## TCI Acid activator
Buty(chloro)dimethyl Silane, ##STR00032## TCI Acid activator
Chloro-decyl-dimethyl Silane ##STR00033## TCI Acid activator
Chloro(chloromethyl)dimethyl ##STR00034## TCI Acid activator
Chloro(dichloromethyl) dimethylsilane ##STR00035## Alfa Aesar Acid
activator Pentafluoropropionic acid ##STR00036## Sigma Non chloride
Acid activator Trifluoroacetic acid ##STR00037## Sigma Non chloride
Acid activator Trichloroacetic acid ##STR00038## Sigma Acid
activator Trichlorododecyl silane (TCSA) ##STR00039## Sigma Aldrich
Acid activator Trichloro(octadecyl) silane
CH.sub.3(CH.sub.2).sub.16CH.sub.2SiCl.sub.3 Sigma Acid Aldrich
activator Dichlorodiphenyl silane ##STR00040## Sigma Aldrich Acid
activator Perfluoro decylmethychloro silane ##STR00041## Acros Acid
activator Perfluoro decylmethyl dichlorosilane ##STR00042## Acros
Acid activator
Romp Inhibitors:
ROMP inhibitors, as described herein, are typically Lewis base
compounds such as triphenyl phosphine (TPP), trialkylphosphite, for
example, triethyl phosphite, thriisorpopryl phosphite, tributyl
phosphite, and tricyclohexyl phosphine, and pyridine.
Any other ROMP inhibitors are contemplated.
The Modeling Material Formulations:
According to some of any of the embodiments described herein, the
building material comprises two or more modeling material
formulations which, upon being dispensed, can undergo a ROMP
reaction.
According to some of any of the embodiments described herein, the
building material comprises two or more modeling material
formulations which form a ROMP system as described herein.
As is known in the art and discussed briefly hereinabove, once an
active catalyst contacts a ROMP monomer, the polymerization
reaction typically starts immediately, sometime without application
of a curing energy, and hence modeling material formulations in
which an active catalyst, as described herein, is utilized "as is",
are inapplicable for 3D inkjet printing.
Embodiments of the present invention therefore relate to modeling
material formulations which are designed such that, prior to
exposure to a suitable condition, the ROMP system is inactive, that
is a ROMP catalyst does not initiate ROMP of the monomer, and a
ROMP monomer does not polymerize via ROMP to provide a respective
polymer, as described herein.
Embodiments of the present invention therefore relate to modeling
material formulations which are designed such that, prior to
exposure to a suitable condition, the ROMP reaction is not
initiated by an active catalyst, that is, prior to exposure to a
suitable condition, at least 50%, preferably at least 60%,
preferably at least 70%, at least 80%, at least 90%, at least 95%
and even 100% of the ROMP monomers do not undergo polymerization.
In other words, prior to exposure of a ROMP system to a suitable
condition, no more than 40% or no more than 30% or no more than 20%
or no more than 10% or no more than 5% of the monomer polymerizes
via ROMP mechanism to provide a respective polymer.
Such modeling material formulations are characterized by a
viscosity of no more than 35 centipoises, or no more than 25
centipoises at a temperature of the inkjet printing head during the
dispensing.
In some embodiments, such modeling material formulations are
characterized by the indicated viscosity at a temperature lower
than 70.degree. C. or lower than 65.degree. C., or lower than
60.degree. C., or lower than 50.degree. C., or lower than
40.degree. C. or lower than 30.degree. C. and even at room
temperature (e.g., 25.degree. C.). Such a viscosity is indicative
of the presence (e.g., of more than 80%) of non-polymerizable ROMP
monomers in the formulation, or of the absence (e.g., less than 20%
of the formulation) of polymeric materials obtained by ROMP in the
formulation.
The modeling material formulations described herein are therefore
designed such that ROMP of the ROMP monomers is not effected when
the formulations pass through the inkjet printing heads.
Embodiments of the present invention further relate to modeling
material formulations which are designed such that, upon exposure
to a suitable condition (an inducing condition as described
herein), the ROMP system becomes active, that is a ROMP catalyst is
active towards ROMP of the monomer, and a ROMP monomer undergo
polymerization via ROMP to provide a respective polymer.
Embodiments of the present invention relate to modeling material
formulations which are designed such that, upon exposure to a
suitable condition, the catalyst is active towards initiation of
the ROMP reaction, that is, upon exposure to a suitable condition,
at least 50%, preferably at least 60%, preferably at least 70%, at
least 80%, at least 90%, at least 95% and even 100% of the ROMP
monomers undergo polymerization via ROMP reaction.
Some embodiments of the present invention relate to modeling
material formulations which are designed such that upon exposure to
a suitable condition, at least 50%, preferably at least 60%,
preferably at least 70%, at least 80%, at least 90%, at least 95%
and even 100% of the ROMP monomers undergo polymerization via ROMP
reaction, within a time period of less than 2 minutes, preferably
less than 1 minute, preferably less than 50 seconds, preferably
less than 40 seconds, and more preferably less than 30 seconds or
less.
In some of any of the embodiments described herein, the building
material comprises two or more a modeling material formulations.
Such embodiments are also referred to herein as "dual jetting" or
"multi jetting" methodology or approach.
In some of these embodiments, each of the modeling material
formulations comprises only ROMP monomers as curable materials.
Such embodiments are also referred to herein as "dual jetting
single curing" or "multi-jetting single curing" methodology or
approach.
Generally, in the above terminology, "jetting" refers to the number
of modeling material formulations included in the building
material, and "curing" refers to the number of polymerization
reactions that occur when the dispensed layers are exposed to a
curing condition (e.g., a ROMP inducing condition, or a ROMP
inducing condition and one or more additional curing
conditions).
It is to be noted that dual curing or multi curing refers herein to
the type of polymerization reactions and not to the number of
conditions applied for inducing curing.
In some of any of the embodiments described herein, the building
material comprises two or more modeling material formulations which
are dispensed from different inkjet printing heads (each
formulation is jetted from a different printing head or a different
set of printing heads) to form the layers.
Such a methodology, which is referred to herein as dual jetting,
when two different modeling material formulations are used, or as
multi-jetting, when more than two modeling material formulations
are used, allows dispensing modeling material formulations which
are absent of one or more of the components required for a
polymerization or curing to occur, whereby when the formulations
are dispensed and contact one another, curing and/or polymerization
occurs.
In the context of some of the present embodiments, such a
methodology allows separating ROMP components as described herein
by including a different combination of components in each
formulation, whereby none of the formulations comprises all the
components required for the ROMP reaction to occur. According to
these embodiments, a ROMP reaction, and optionally non-ROMP
reactions, occur only on the receiving medium, and after the
building material is dispensed.
In some of these embodiments, exposing the formulation to a
condition for initiating ROMP can be effected by contacting the
different formulations on the receiving medium (receiving tray). In
some of these embodiments, exposing to a ROMP inducing condition is
effected by dispensing the formulations.
Connex 3.TM. (Stratasys Ltd., Israel) multiple material deposition
technology, is an exemplary technology that provides the
possibility to separate the components of a polymerizable or
curable system into different formulations. Objet Connex 3.TM.
(Stratasys Ltd., Israel) multiple material deposition system, is a
system that allows utilizing such a technology.
The two or more modeling material formulations usable in these
embodiments are also referred to herein as a modeling material
formulation system or as a modeling material system or as a
formulation system.
In some of any of these embodiments, the building material
comprises two or more modeling material formulations, and the two
or more modeling material formulations are such that when combined,
curing is effected by ROMP reaction.
In some of these embodiments, each of the modeling material
formulations comprises a ROMP monomer (which can be the same or
different).
In some of these embodiments, each of the modeling material
formulations comprises a ROMP monomer (which can be the same or
different), and one of the formulations further comprises a ROMP
pre-catalyst which is an acid-activatable. Ru-based, pre-catalyst
as described herein in any of the respective embodiments.
In some of these embodiments, the building material comprises more
than two the modeling material formulations, each independently
comprising a ROMP monomer (which can be the same or different), and
one or two of these formulations further comprises a ROMP
pre-catalyst, as described herein.
In some of any of these embodiments, one or more of the modeling
material formulations is devoid of a ROMP pre-catalyst, and in some
embodiments, one or more of the modeling material formulations
comprises a ROMP monomer and a ROMP pre-catalyst.
In some of these embodiments, each of the modeling material
formulations independently comprises a ROMP monomer, one or more of
the formulations further comprise a pre-catalyst, and one or more
other formulations further comprise(s) an activator. In some of
these embodiments, the one or more formulations that comprise the
activator are devoid of the pre-catalyst. In some embodiments, the
one or more formulations that comprise the pre-catalyst are devoid
of an activator.
In some of these embodiments, exposing the dispensed layers to
inducing condition is effected by contacting the formulations on
the receiving medium, and hence comprises the formation of the
dispensed layers (e.g., by jetting the modeling material
formulation by the inkjet printing heads).
In some of any of the embodiments described herein, one or more, or
each, of the modeling material formulations further comprises a
ROMP inhibitor.
In some of any of the embodiments described herein, one or more, or
each, of the modeling material formulations, further comprises
additional materials, as is described in further detail
hereinunder.
In some of any of the embodiments described herein, a concentration
of a ROMP monomer (or monomers), in a modeling material formulation
containing same ranges from about 50% to about 99%, or from about
60% to about 99%, or from about 70% to about 99%, or from about 80%
to about 99%, or from about 85% to about 99%, or from about 85% to
about 95%, by weight of the total weight of the modeling material
formulation, including any subranges and intermediate values
therebetween. In exemplary embodiments, a concentration of a ROMP
monomer (or monomers), in a modeling material formulation
containing same ranges from 90% to 92%, of the total weight of the
formulation. The indicated concentration ranges refer to a total
weight percents of the ROMP monomers, in case more than one ROMP
monomer is included.
In some of any of the embodiments described herein, a concentration
of a ROMP pre-catalyst or a total concentration of ROMP
pre-catalysts in case a mixture of pre-catalysts is used, in a
modeling material formulation containing same independently ranges
from about 0.001% to about 1%, or from about 0.001% to about 0.1%,
or from about 0.01% to about 0.1%, or is about 0.05%, by weight of
the total weight of the modeling material formulation, including
any subranges and intermediate values therebetween.
In some embodiments, a concentration of a ROMP inhibitor in a
modeling material formulation containing same independently ranges
from about 0.001% to about 1%, or from about 0.001% to about 0.1%
by weight of the total weight of the modeling material formulation,
including any subranges and intermediate values therebetween. In
some embodiments, the concentration of a ROMP inhibitor ranges from
about 1 to about 200 ppm, or from about 1 to about 100 ppm, or from
about 1 to about 60 ppm, or from about 1 to about 40 ppm, or from
about 10 to about 20 ppm of the total weight of the modeling
material formulation, including any subranges and intermediate
values therebetween.
In some embodiments, a concentration of a ROMP activator as
described herein in a modeling material formulation containing same
independently ranges from about 0.001% to about 5%, or from about
0.001% to about 2%, or from about 0.01% to about 2%, or from about
0.01% to about 1%, or from about 0.01 to about 0.5%, or from about
0.01 to about 0.2%, or is about 0.08%, by weight, of the total
weight of the modeling material formulation, including any
subranges and intermediate values there between.
In some of any of the embodiments described herein, a curable
material (a ROMP monomer) can be a monofunctional curable material,
which comprises one polymerizable group that participates in the
ROMP reaction, and/or a bifunctional or multifunctional curable
material, which comprises two or more polymerizable groups that
participate in the ROMP reaction.
Additional Materials:
In some of any of the embodiments described herein, one or more of
the modeling material formulations further comprise(s) one or more
additional material(s), which are referred to herein also as
non-reactive or non-curable materials, that is, materials which do
not undergo polymerization and/or curing.
Such agents include, for example, surface active agents,
stabilizers, antioxidants, fillers, pigments, dispersants, and/or
toughening agents (or toughness modifiers, for example, impact
modifying agents).
The non-reactive agents can be independently included in one or all
(e.g., both) of the modeling material formulations.
The term "filler" describes an inert material that modifies the
properties of a polymeric material and/or adjusts a quality of the
end products. The filler may be an inorganic particle, for example
calcium carbonate, silica, and clay.
Fillers may be added to the modeling formulation in order to reduce
shrinkage during polymerization or during cooling, for example, to
reduce the coefficient of thermal expansion, increase strength,
increase thermal stability, reduce cost and/or adopt rheological
properties. Nanoparticle fillers are typically useful in
applications requiring low viscosity such as ink-jet
applications.
In some embodiments, a modeling formulation comprises a surface
active agent. A surface-active agent may be used to reduce the
surface tension of the formulation to the value required for
jetting or for printing process, which is typically around 10-50
dyne/cm. An exemplary such agent is a silicone surface
additive.
Suitable stabilizers (stabilizing agents) include, for example,
thermal stabilizers, which stabilize the formulation at high
temperatures.
In some embodiments, the modeling formulation comprises one or more
pigments. In some embodiments, the pigment's concentration is lower
than 35%, or lower than 25% or lower than 15%, by weight.
The pigment may be a white pigment. The pigment may be an organic
pigment or an inorganic pigment, or a metal pigment or a
combination thereof.
In some embodiments the modeling formulation further comprises a
dye.
In some embodiments, combinations of white pigments and dyes are
used to prepare colored cured materials.
The dye may be any of a broad class of solvent soluble dyes. Some
non-limiting examples are azo dyes which are yellow, orange, brown
and red; anthraquinone and triarylmethane dyes which are green and
blue; and azine dye which is black.
In some of any of the embodiments described herein, one or more of
the modeling material formulations comprises a toughening agent or
a mixture of toughening agents.
The phrase "toughening agent" is also referred to herein as a
"toughness modifying agent" or "toughness modifier" and encompasses
one or more (e.g., a mixture of two or more) toughening agents and
is used herein to describe agents that modify (e.g., improve) the
toughness of a material containing same.
In some embodiments, the toughness is reflected by Impact
resistance and/or tensile strength.
In some embodiments, a toughness modifying agent (a toughening
agent) improves the Impact resistance and/or Tensile strength of a
material containing same. In some embodiments, a toughness
modifying agent (a toughening agent) improves the Impact resistance
of a material containing. In some embodiments, a toughness
modifying agent (a toughening agent) improves the Tensile strength
of a material containing same. In some embodiments, a toughness
modifying agent (a toughening agent) improves the Impact resistance
and the Tensile strength of a material containing same.
The phrase "toughening agent" encompasses materials referred to
herein as "Impact modifying agents" or "Impact modifiers".
According to some of any of the embodiments of the present
invention, the toughening agent (e.g., Impact modifying agent) is
an elastomeric material.
The phrase "elastomeric material" is also referred to herein and in
the art interchangeably as "elastomer" and encompasses deformable,
viscoelastic polymeric materials (typically co-polymers), including
rubbers, liquid rubbers and rubbery-like materials. In some
embodiments, an elastomeric material as described herein comprises
saturated and/or unsaturated hydrocarbon chains, preferably long
hydrocarbon chains of at least 20 carbon atoms in length. In some
embodiments, the hydrocarbon chains do not include heteroatoms
(e.g., oxygen, nitrogen, sulfur) interrupting the chain or forming
a part of the substituents of the chain.
In some embodiments, by "hydrocarbon" it is meant herein a material
containing one or more chains comprised mainly (e.g., 80%, or 85%
or 90%, or 95%, or 100%) of carbon and hydrogen atoms, linked to
one another. Exemplary hydrocarbons include one or more alkyl,
cycloalkyl and/or aryl moieties covalently linked to one another in
any order.
Non-limiting examples of toughening agents include elastomeric
materials such as, but not limited to, natural rubber, butyl
rubber, polyisoprene, polybutadiene, polyisobutylene,
ethylene-propylene copolymer, styrene-butadiene-styrene triblock
rubber, random styrene-butadiene rubber, styrene-isoprene-styrene
triblock rubber, styrene-ethylene/butylene-styrene copolymer,
styrene-ethylene/propylene-styrene copolymer,
ethylene-propylene-diene terpolymers, ethylene-vinyl acetate and
nitrile rubbers. Preferred agents are elastomers such as
polybutadienes.
Toughening agents such as elastomeric materials can be added to the
formulation by incorporating in one or more of the modeling
material formulations an elastomeric material in a
dispersed/dissolved phase.
According to some of any of the embodiments described herein, the
elastomeric material is characterized by at least one, at least
two, or all of the following: featuring a molecular weight lower
than 50,000, or lower than 40,000, or, preferably, lower than
30,000, or lower than 20,000, or lower than 10,000 Daltons;
being non-reactive towards ROMP;
being dissolvable or dispersible in the one or more modeling
material formulation(s) containing same; and
being capable of forming a multiphase (e.g., biphasic) structure
when blended with the cured modeling material.
According to some of any of the embodiments described herein, the
elastomeric material is dissolvable or dispersible in the modeling
material formulation comprising same.
ROMP monomers and formulations containing same are typically
hydrophobic. Therefore, in some embodiments, an elastomeric
material which is dissolvable or dispersible in a modeling material
formulation which comprises a ROMP monomer is hydrophobic, and
thereby exhibits compatibility, and dissolvability or
dispersibility in the ROMP monomer formulation, which has a
hydrophobic nature.
According to some of any of the embodiments described herein, the
elastomeric material is selected capable of forming a multiphase
(e.g., biphasic) structure when blended with the cured modeling
material.
As is known in the art. Impact resistance can be improved in case
of a phase separation between the impact modifying agent and the
polymeric matrix with which it is blended, namely, in case where
there is a biphasic or multiphasic structure of the blend.
In some embodiments, an elastomeric material that is capable of
forming a multiphase (e.g., biphasic) structure when blended with
the cured modeling material can be regarded as non-soluble in the
polymeric matrix formed upon exposing the modeling material
formulation(s) to curing condition, namely, in the cured (or
partially cured) modeling material.
According to some of any of the embodiments described herein, the
elastomeric material is selected such that it is dissolvable or
dispersible in the modeling material comprising same, and is
further capable of forming a multiphase (e.g., biphasic) structure
when blended with the cured modeling material.
In some of the embodiments pertaining to an elastomeric material
that is capable of forming a multiphasic structure when blended
with the cured modeling material, the ROMP monomer is or comprises
a DCPD or a derivative thereof, as described herein.
According to some of any of the embodiments described herein, the
elastomeric material is an impact modifying agent (Impact
modifier).
It is to be noted that phase separation is not required for an
Impact modifying agent to provide its effect in all cases. That is,
when an elastomeric material is blended with a cured modeling
material formed of a ROMP monomer-containing modeling material
formulation(s). Impact resistance can be improved also when there
is no phase separation (no biphasic or multiphasic structure is
formed).
According to some of any of the embodiments described herein, the
elastomeric material is non-reactive towards ROMP. By "non-reactive
towards ROMP" it is meant that the elastomeric material does
feature functional groups that can participate in ROMP. As known in
the art, ROMP involves materials featuring unsaturated bonds.
Accordingly, exemplary elastomeric materials which are non-reactive
towards ROMP are saturated polymeric materials, namely, polymers
and/or copolymers which do not comprise unsaturated bonds in their
backbone chain. The pendant groups of such elastomeric materials
may or may not comprise unsaturated bonds.
Elastomeric materials featuring a saturated backbone chain, namely,
are devoid of unsaturated bonds in their backbone chain, are
defined herein as "saturated" elastomeric materials.
In some of the embodiments pertaining to an elastomeric material
that is non-reactive towards ROMP, the ROMP monomer is or comprises
a DCPD or a derivative thereof, as described herein.
According to some embodiments of the present invention, the
elastomeric material is a low molecular weight material, as defined
herein, which is a saturated polymer or co-polymer.
According to some embodiments of the present invention, the
elastomeric material is a low molecular weight material, as defined
herein, which is hydrophobic.
According to some embodiments of the present invention, the
elastomeric material is a low molecular weight material, as defined
herein, which is a saturated polymer or co-polymer and which is
further characterized as hydrophobic.
According to some of these embodiments the elastomeric material is
further characterized as dissolvable or dispersible in the modeling
material formulation containing same and optionally further as
forming a biphasic structure with the cured modeling material.
Exemplary elastomeric materials suitable for use according to some
of the present embodiments include, but are not limited to, low MW
EPDM such as Trilene 67 (MW=37,000 Da) or Trilene 77 (MW=27,000
Da), liquid EPR elastomers such as Trilene CP80 (MW=23,000 Da) or
Trilene CP1100 (MW=6600 Da), low MW polybutenes, low MW
polyisoprenes, and the like. Preferred exemplary elastomeric
materials include, but are not limited to, liquid EPR elastomers
and polybutenes, having MW lower than 20,000 or lower than 12,000
Daltons.
According to some of any of the embodiments, a concentration of the
toughening agent (e.g., an elastomeric material as described
herein), if present, may range from about 0.1% to about 20%, or
from about 1 to about 20%, or from about 1 to about 15%, or from
about 1 to about 12%, or from about 1 to about 10%, or from about 2
to about 10%, or from about 2 to about 8%, by weight, of the total
weight of a formulation containing same, including any intermediate
values and subranges therebetween.
A concentration of the toughening agent (e.g. elastomeric
materials), if present, may range from about 0.10 phr to about 10
phr, or from about 0.1 phr to about 5 phr, relative to the weight
of the formulation containing same.
A concentration of the toughening agent (e.g. elastomeric material)
may alternatively range from about 0.1% to about 20%, or from about
1% to about 20%, or from about 1% to about 20%, or from about 5% to
about 15% or from about 5% to about 10%, by weight, of the total
weight of a formulation containing same, including any intermediate
values and subranges therebetween.
In some embodiments, each of the modeling material formulations
comprises an elastomeric material, as described herein.
Exemplary elastomers are presented in Table D below.
Other impact modifying agents, such as, for example, carbon fibers,
carbon nanotubes, nanoparticles, glass fibers, aramid Keylar,
polyparaphenylene benzobisoxazole Zylon, and other polar and non
polar impact modifiers, are also contemplated as toughening agents
as described herein.
Alternatively, or in addition, elastomeric materials other than the
elastomeric materials described herein can be included. In some
embodiments, a concentration of such elastomeric materials, if
present, is lower than a concentration of the elastomeric materials
described herein.
In some embodiments, one or more, or each, of the modeling material
formulation comprises an antioxidant. In some embodiments, at least
a modeling material formulation that comprises the pre-catalyst
comprises an anti-oxidant. Exemplary antioxidants are presented in
Table D below.
In some embodiments, one or more, or each, of the modeling material
formulation comprises a proton donor. Proton donors are useful for
accelerating the activation of the pre-catalyst by the activator,
to thereby accelerate the ROMP reaction. For example, a proton
donor, when contacted with a chlorosilane activator as described
herein generates HCl, which accelerates the activation of the
pre-catalyst.
The proton donors can be reactive (curable) or non-reactive.
Curable proton donors include, for example, ROMP monomers which
bear acidic protons (e.g. hydroxy groups).
Exemplary reactive and non-reactive proton donors are presented in
Table D below. In some embodiments, the proton donor is a hydroxy
alkyl, for example, 1-butanol.
A concentration of the proton donor can range from about 0.1 to
about 2%, by weight, of a modeling material formulation containing
same, including any intermediate values and subranges
therebetween.
In some embodiments, a proton donor is included in a modeling
material formulation which is devoid of the activator (e.g., a
modeling material formulation which comprises a pre-catalyst).
Table D below presents exemplary non-reactive components suitable
for inclusion in any one or all of the modeling material
formulations described herein.
TABLE-US-00004 TABLE D Tradename Material Supplier Function Trilene
CP1100 Liquid EPR Lion Impact copolymer modifier Trilene CP80
Liquid EPR Lion Impact copolymer modifier Trilene 77 Liquid EPDM
Lion Impact copolymer modifier Trilene 67 Liquid EPDM Lion Impact
copolymer modifier Trilene 65 Liquid EPDM Lion Impact copolymer
modifier Ethanox 702 4,4'-Methylenebis Albemarle Antioxidant,
(2,6-di-tert- Radical butylphenol) scavenger BHT 2,6-Bis(1,1- Sigma
Antioxidant, dimethylethyl)-4- Aldrich Radical methylphenol
scavenger NIPOL 13121 Liquid NBR ZEON Impact modifier NIPOL 1312LV
Liquid NBR ZEON Impact modifier NIPOL 13122 Liquid NBR ZEON Impact
modifier 1-butanol Sigma Proton Aldrich donor 2-butanol Sigma
Proton Aldrich donor Tert-butanol Sigma Proton Aldrich donor
Propanol Sigma Proton Aldrich donor Iso-propanol Sigma Proton
Aldrich donor Ethanol Sigma Proton Aldrich donor 5-Norbornene-
2,3-dimethanol ##STR00043## Sigma Aldrich Reactive proton donor
5-Norbornene- 2-methanol ##STR00044## Sigma Aldrich Reactive proton
donor 5-Norbornen- 2-ol ##STR00045## Sigma Aldrich Reactive proton
donor 5-Norbornene- 2,2-dimethanol ##STR00046## Sigma Aldrich
Reactive proton donor
Exemplary Modeling Material Formulations:
In some of any of the embodiments described herein, the modeling
material formulation system comprises two modeling material
formulations.
In some of these embodiments, a first modeling material formulation
(also referred to herein as Part A) comprises a ROMP monomer as
described herein (e.g., a RIM monomer), and a pre-catalyst as
described herein (e.g., a mixture of two pre-catalysts as described
herein).
In some of these embodiments, the first formulation further
comprises a toughening agent as described herein, and a ROMP
inhibitor, as described herein, and optionally further comprises an
antioxidant and/or a proton donor. In some of these embodiments,
the toughening agent is an elastomer or an elastomeric material, as
described herein in any of the respective embodiments.
In some of any of these embodiments, a second modeling material
formulation (also referred to herein as Part B) comprises a ROMP
monomer as described herein (e.g., a RIM monomer), and an activator
(e.g., an organic chlorosilane), as described herein.
In some of these embodiments, the second formulation further
comprises a toughening agent as described herein. In some of these
embodiments, the toughening agent is an elastomer or an elastomeric
material, as described herein in any of the respective
embodiments.
In exemplary embodiments, the first formulation comprises a ROMP
monomer as described herein (e.g., a RIM monomer), at a
concentration of from 50 to 99% or from 70 to 99%, by weight, and a
pre-catalyst as described herein (e.g., a mixture of two
pre-catalysts as described herein), at a concentration of from 0.01
to 0.1% by weight, and optionally further comprises a ROMP
inhibitor as described herein, at a concentration of 1 to 200 ppm,
or 1 to 60 ppm, as described herein, a toughening agent (e.g., an
elastomeric material as described herein) at a concentration of
from 0.1 to 20%, by weight, and/or an anti-oxidant, at a
concentration of 0.01-5%, by weight, and/or a filler as described
herein, at a concentration of 0.01-20% by weight, of the total
weight of the formulation.
In some of any of these embodiments, a second modeling material
formulation (also referred to herein as Part B) comprises a ROMP
monomer as described herein (e.g., a RIM monomer), which can be the
same or different from the ROMP monomer included in the first
formulation, and a ROMP activator (e.g., an organic chlorosilane),
as described herein in any of the respective embodiments.
In some of these embodiments, the second formulation further
comprises a toughening agent as described herein. In some of these
embodiments, the toughening agent is an elastomer or an elastomeric
material, as described herein in any of the respective
embodiments.
In exemplary embodiments, the second formulation comprises a ROMP
monomer as described herein (e.g., a RIM monomer), at a
concentration of from 50 to 99% or from 70 to 99%, by weight, and a
ROMP activator as described herein (e.g., an organic chlorosilane),
at a concentration of from 0.01 to 2% by weight, and optionally
further comprises a toughening agent (e.g., an elastomeric material
as described herein) at a concentration of from 0.1 to 20%, by
weight, and/or a filler as described herein, at a concentration of
0.01-20% by weight, of the total weight of the formulation.
In some of these embodiments, the first formulation is devoid of an
activator.
In some of these embodiments, the second formulation is devoid of a
pre-catalyst.
The modeling material formulation system described herein provides
formulations which exhibit desirable shelf-life, stability and
reactivity, such that no substantial change in the formulations'
viscosity and reactivity occurs during printing (e.g., in printing
block and printing heads), yet an efficient printing process can be
performed due to rapid hardening of the dispensed layers of the
formulations.
Moreover, the modeling material formulations described herein can
be utilized only with components of a ROMP system, without the need
to introduce non-ROMP curable materials that may interfere with the
ROMP reaction, although this is not obligatory.
The use of components of a ROMP system only allows fabrication of
3D objects which feature physic-mechanical properties such as
Impact resistance and HDT which supersede properties obtained with
other curable systems.
Kits:
According to some of any of the embodiments described herein, there
are provided kits containing the modeling material formulations as
described herein.
In some embodiments, a kit comprises a modeling material
formulation system for use in a dual or multi-jetting methodology,
as described herein. The components of each of the modeling
material formulations (the first and second formulations, or Part A
and Part B) are packaged individually in the kit and include a ROMP
monomer or monomers, as described in any of the respective
embodiments, a ROMP pre-catalyst, and an activator, as described
herein in any of the respective embodiments.
In exemplary embodiments, each of the first and the second
formulations as described herein is individually packaged in a
suitable packaging material, preferably, an impermeable material
(e.g., water- and gas-impermeable material), and further preferably
an opaque material; and both formulations are packaged together in
the kit. In some embodiments, the kit further comprises
instructions to use the formulations in an additive manufacturing
process, preferably a 3D inkjet printing process as described
herein. The kit may further comprise instructions to use the
formulations in the process in accordance with the method as
described herein. In some embodiments, the kits include
instructions to avoid contact between the first and second
formulations at any stage before printing is effected (e.g., before
the formulations are dispensed from the nozzles).
In some embodiments the kit comprises two or more modeling material
formulations, at least one of the formulations comprises a ROMP
monomer as described herein in any of the respective embodiments,
at least one of the formulations comprises a ROMP pre-catalyst, as
described herein in any of the respective embodiments, and at least
one of the formulations comprises a ROMP activator as described
herein in any of the respective embodiments, wherein the ROMP
activator and the ROMP pre-catalyst are not in the same
formulation.
In some of these embodiments, a first modeling material formulation
(also referred to herein as Part A) comprises a ROMP monomer as
described herein (e.g., a RIM monomer), and a pre-catalyst as
described herein (e.g., a mixture of two pre-catalysts as described
herein).
In some of these embodiments, the first formulation further
comprises a toughening agent as described herein, and a ROMP
inhibitor, as described herein, and optionally further comprises an
antioxidant and/or a proton donor. In some of these embodiments,
the toughening agent is an elastomer or an elastomeric material, as
described herein in any of the respective embodiments.
In exemplary embodiments, the first formulation comprises a ROMP
monomer as described herein (e.g., a RIM monomer), at a
concentration of from 50 to 99% or from 70 to 99%, by weight, and a
pre-catalyst as described herein (e.g., a mixture of two
pre-catalysts as described herein), at a concentration of from 0.01
to 0.1% by weight, and optionally further comprises a ROMP
inhibitor as described herein, at a concentration of 1 to 200 ppm,
or 1 to 60 ppm, as described herein, a toughening agent (e.g., an
elastomeric material as described herein) at a concentration of
from 0.1 to 20%, by weight, and/or an anti-oxidant, at a
concentration of 0.01-5%, by weight, and/or a filler as described
herein, at a concentration of 0.01-20% by weight, of the total
weight of the formulation.
In some of any of these embodiments, a second modeling material
formulation (also referred to herein as Part B) comprises a ROMP
monomer as described herein (e.g., a RIM monomer), which can be the
same or different from the ROMP monomer included in the first
formulation, and a ROMP activator (e.g., an organic chlorosilane),
as described herein in any of the respective embodiments.
In some of these embodiments, the second formulation further
comprises a toughening agent as described herein. In some of these
embodiments, the toughening agent is an elastomer or an elastomeric
material, as described herein in any of the respective
embodiments.
In exemplary embodiments, the second formulation comprises a ROMP
monomer as described herein (e.g., a RIM monomer), at a
concentration of from 50 to 99% or from 70 to 99%, by weight, and a
ROMP activator as described herein (e.g., an organic chlorosilane),
at a concentration of from 0.01 to 2% by weight, and optionally
further comprises a toughening agent (e.g., an elastomeric material
as described herein) at a concentration of from 0.1 to 20%, by
weight, and/or a filler as described herein, at a concentration of
0.01-20% by weight, of the total weight of the formulation.
In some of any of these embodiments, the first formulation is
devoid of an activator.
In some of any of these embodiments, the second formulation is
devoid of a pre-catalyst.
The Object:
According to an aspect of some embodiments of the present invention
there is provided a three-dimensional object which comprises a
polymeric material obtainable by ROMP of respective ROMP monomer or
combination of ROMP monomers. In some of these embodiments, the 3D
object is obtainable by 3D inkjet printing.
According to an aspect of some embodiments of the present invention
there is provided a three-dimensional object fabricated by a 3D
inkjet printing process, which is characterized by an impact
resistance of at least 80 J/m.
In some embodiments, the object is characterized by an impact
resistance of at least 100, at least 150, at least 180, at least
200 J/m, and even higher impact resistance
Herein throughout and in the art, the phrase "impact resistance",
which is also referred to interchangeably, herein and in the art,
as "impact strength" or simply as "impact", describes the
resistance of a material to fracture by a mechanical impact, and is
expressed in terms of the amount of energy absorbed by the material
before complete fracture. Impact resistance can be measured using,
for example, the ASTM D256-06 standard Izod impact testing (also
known as "Izod notched impact", or as "Izod impact"), and/or as
described hereinunder, and is expressed as J/m.
In some embodiments, the object is characterized by heat deflection
temperature (HDT) which is at least 50, at least 60, at least 60,
at least 70, at least 80, at least 90, at least 100, at least 110,
at least 120, at least 130.degree. C., and even higher.
Herein throughout and in the art, the phrase "heat deflection
temperature", or HDT, describes the temperature at which a specimen
of cured material deforms under a specified load. Determination of
HDT can be performed using the procedure outlined in ASTM
D648-06/D648-07 and/or as described hereinunder.
The fabrication of 3D objects by a 3D inkjet printing process is
enabled by the use of ROMP systems, as described herein.
In some embodiments, the 3D object further comprises, in at least a
part thereof, a material featuring antioxidation, for example, in a
form of a layer deposited on the surface of the object or a part
thereof as described herein.
The Printing System:
FIG. 2 is a schematic illustration of a system 110 suitable for 3D
inkjet printing of an object 112 according to some embodiments of
the present invention. System 110 comprises a printing apparatus
114 having a printing unit 116 which comprises a plurality of
printing heads. Each head preferably comprises an array of one or
more nozzles 122, as illustrated in FIGS. 3A-C described below,
through which a liquid (uncured) building material 124 is
dispensed. Preferably, apparatus 114 is a three-dimensional inkjet
printing apparatus. FIGS. 3A-B illustrate a printing head 116 with
one (FIG. 3A) and two (FIG. 3B) nozzle arrays 22. The nozzles in
the array are preferably aligned linearly, along a straight line.
In embodiments in which a particular printing head has two or more
linear nozzle arrays, the nozzle arrays are optionally and
preferably can be parallel to each other. In some embodiments, two
or more printing heads can be assembled to a block of printing
heads, in which case the printing heads of the block are typically
parallel to each other. A block including several inkjet printing
heads 116a, 116b, 116c is illustrated in FIG. 3C. Printing heads
116 are optionally and preferably oriented along the indexing
direction with their positions along the scanning direction being
offset to one another.
Each printing head is optionally and preferably fed via a building
material reservoir which may optionally include a temperature
control unit (e.g., a temperature sensor and/or a heating device),
and a material level sensor. To dispense the building material, a
voltage signal is applied to the printing heads to selectively
deposit droplets of material via the printing head nozzles, for
example, as in piezoelectric inkjet printing technology. The
dispensing rate of each head depends on the number of nozzles, the
type of nozzles and the applied voltage signal rate (frequency).
Such printing heads are known to those skilled in the art of solid
freeform fabrication.
Preferably, but not obligatorily, the overall number of printing
nozzles or nozzle arrays is selected such that half of the printing
nozzles are designated to dispense support material formulation(s)
and half of the printing nozzles are designated to dispense
modeling material formulation(s). i.e. the number of nozzles
jetting modeling material formulations is the same as the number of
nozzles jetting support material formulations. In the
representative example of FIG. 2, four printing heads 116a. 116b,
116c and 116d are illustrated. Each of heads 116a, 116b, 116c and
116d has a nozzle array. In this Example, heads 116a and 116b can
be designated for modeling materials and heads 116c and 116d can be
designated for support material. Thus, head 116a can dispense a
first modeling material formulation, head 116b can dispense a
second modeling material formulation and heads 116c and 116d can
both dispense a support material formulation. In an alternative
embodiment, heads 116c and 116d, for example, may be combined in a
single head having two nozzle arrays for depositing a support
material formulation. Preferably, heads designated to dispense
different modeling material formulations are physically separated
from each other in a manner that prevents the different modeling
material formulations from mixing before they are dispensed out of
the heads.
It is to be understood that it is not intended to limit the scope
of the present invention and that the number of modeling material
formulations depositing heads (modeling heads) and the number of
support material depositing heads (support heads) may differ.
Generally, the number of modeling heads, the number of support
heads and the number of nozzles in each respective head or head
array are selected such as to provide a predetermined ratio, a,
between the maximal dispensing rate of the support material and the
maximal dispensing rate of modeling material. The value of the
predetermined ratio, a, is preferably selected to ensure that in
each formed layer, the height of modeling material equals the
height of support material. Typical values for a are from about 0.6
to about 1.5.
For example, for a=1, the overall dispensing rate of support
material is generally the same as the overall dispensing rate of
the modeling material when all modeling heads and support heads
operate.
In a preferred embodiment, there are M modeling heads each having m
arrays of p nozzles, and S support heads each having s arrays of q
nozzles such that M.times.m.times.p=S.times.s.times.q. Each of the
M.times.m modeling arrays and S.times.s support arrays can be
manufactured as a separate physical unit, which can be assembled
and disassembled from the group of arrays. In this embodiment, each
such array optionally and preferably comprises a temperature
control unit and a material level sensor of its own, and receives
an individually controlled voltage for its operation.
Apparatus 114 can further comprise a hardening device 324 which can
include any device configured to emit light, heat or any other
curing energy that may cause the deposited material to harden. For
example, hardening device 324 can comprise one or more radiation
sources, which can be, for example, an infrared lamp or any other
source emitting heat-inducing radiation, as further detailed
hereinabove, a UV radiation source. In some embodiments of the
present invention, hardening device 324 serves for applying a
curing condition to the modeling material.
The printing head and radiation source are preferably mounted in a
frame or block 128 which is preferably operative to reciprocally
move over a tray 360, which serves as the working surface.
Apparatus 114 can further comprise a tray heater 328 configured for
heating the tray. These embodiments are particularly useful when
the modeling material is hardened by heating (exposure to
heat).
In some embodiments of the present invention the radiation sources
are mounted in the block such that they follow in the wake of the
printing heads to at least partially cure or solidify the materials
just dispensed by the printing heads. Tray 360 is positioned
horizontally. According to the common conventions an X-Y-Z
Cartesian coordinate system is selected such that the X-Y plane is
parallel to tray 360. Tray 360 is preferably configured to move
vertically (along the Z direction), typically downward.
In various exemplary embodiments of the invention, apparatus 114
further comprises one or more leveling devices 132. Leveling device
132 serves to straighten, level and/or establish a thickness of the
newly formed layer prior to the formation of the successive layer
thereon. Leveling device 132 can comprise one or more rollers 326.
Rollers 326 can have a generally smooth surface or can have a
patterned surface. In some embodiments of the present invention one
or more of the layers is straightened while the formulation within
the layer is at a cured or partially cured state. In these
embodiments, leveling device 132 is capable of reforming the
solidified portion of the formulation. For example, when leveling
device 132 comprises one or more rollers at least one of these
rollers is capable of milling, grinding and/or flaking the
solidified portion of the formulation. Preferably, in these
embodiments, the roller has a non-smooth surface so as to
facilitate the milling, grinding and/or flaking. For example, the
surface of the roller can be patterned with blades and/or have a
shape of an auger.
In some embodiments of the present invention one or more of the
layers is straightened while the formulation within the layer is
uncured. In these embodiments, leveling device 132 can comprise a
roller or a blade, which is optionally and preferably, but not
necessarily, incapable of effecting milling, grinding and/or
flaking.
Leveling device 132 preferably comprises a waste collection device
136 for collecting the excess material generated during leveling.
Waste collection device 136 may comprise any mechanism that
delivers the material to a waste tank or waste cartridge.
Optionally, leveling device 132 is a self-cleaning leveling device,
wherein cured or partially cured formulation is periodically
removed from leveling device 132. A representative Example of a
self-cleaning leveling device is illustrated in FIG. 4. Shown in
FIG. 4 is a double roller having a first roller 356 that contacts
and straightens a layer 358 and a second roller 354 that is in
contact with the first roller 356 but not with the layer 358 and
which is configured to remove the formulation from the first roller
358. When first roller 356 has a non-smooth surface, second roller
354 preferably is also non-smoothed wherein the pattern formed on
the surface of roller 354 is complementary to the pattern formed on
the surface of roller 356, so as to allow roller 354 to clean the
surface of roller 358.
Apparatus 114 can also comprise a chamber 350 enclosing at least
heads 116 and tray 360, but may also enclose other components of
system 110, such as, but not limited to, devices 132 and 324, frame
128 and the like. In some embodiments of the present invention
apparatus 114 comprises a chamber heater 352 that heats the
interior of chamber 350 as further detailed hereinabove. Chamber
350 is preferably generally sealed to an environment outside
chamber 350. In some embodiments, a filter, such as, but not
limited to, a carbon filter is used for evacuating vapors out of
chamber 350.
In some embodiments of the present invention chamber 350 comprises
a gas inlet 364 and the system comprises a gas source 366
configured for filling said chamber by an inert gas through gas
inlet 364. Gas source 366 can be a container filled with the inert
gas. The gas can be any of the inert gases described above.
Optionally, chamber 350 is also formed with a gas outlet 368 for
allowing the gas to exit chamber 350 if desired. Both inlet 366 and
outlet 368 of the present embodiments are provided with valves (not
shown) so as to controllably allow entry and/or exit of the gas to
and from chamber 350. Preferably, controller 152 generates,
continuously or intermittently, inflow and outflow of the inert gas
through gas inlet 366 and gas outlet 368. This can be achieved by
configuring controller 152 to control at least one of source 366,
inlet 364 and outlet 368. Optionally, system 110 comprises a gas
flow generating device 370, placed within chamber 350 and
configured for generating a flow of the inert gas within chamber
350. Device 370 can be a fan or a blower. Controller 152 can be
configured for controlling also device 370, for example, based on a
predetermined printing protocol.
In some embodiments of the present invention apparatus 114
comprises a mixing chamber 362 for preparing the modeling material
formulation prior to entry of the modeling material formulation
into a respective head. In the schematic illustration of FIG. 2,
which is not to be considered as limiting, chamber 362 receives
materials from different containers, mixes the received materials
and introduces the mix to two heads (heads 116b and 116a, in the
present example). However, this need not necessarily be the case
since in some embodiments chamber 362 can receive materials from
different containers, mixes the received materials and introduces
the mix only to more than two heads or only to one head.
Preferably, the position and fluid communication between mixing
chamber 362 and respective head is selected such that at least 80%
or at least 85% or at least 90% or at least 95% or at least 99% or
the modeling material formulation that enters the respective head
or heads (e.g., heads 116b and 116a in the present example) remains
uncured. For example, chamber 362 can be attached directly to the
printing head or the printing block, such that motion of the
printing head is accompanied by motion of the mixing chamber. These
embodiments are particularly useful when the formulation undergoes
fast polymerization reaction even in the absence of curing
radiation.
In some embodiments, apparatus 114 comprises a dispensing head
wiper 325, constituted for removing remnant formulations from the
surface of the dispensing heads 116, by wiping. Wiper 325 can
engage the nozzles of heads 116, for example, once the head
completes a movement along the scanning direction or a cycle of
reciprocal movements along the scanning direction. Wiper 325 can be
in the form of a blade, or more preferably, can include a fabric
327 that is wetted by a solvent before engaging the nozzles of head
116. The solvent is selected to facilitate removal of uncured,
partially cured or fully cured formulation from the surface of the
head.
In use, the dispensing heads of unit 116 move in a scanning
direction, which is referred to herein as the X direction, and
selectively dispense building material in a predetermined
configuration in the course of their passage over tray 360. The
building material typically comprises one or more types of support
material and one or more types of modeling material. The passage of
the dispensing heads of unit 116 is followed by the curing of the
modeling material(s) by radiation source 126. In the reverse
passage of the heads, back to their starting point for the layer
just deposited, an additional dispensing of building material may
be carried out, according to predetermined configuration. In the
forward and/or reverse passages of the dispensing heads, the layer
thus formed may be straightened by leveling device 326, which
preferably follows the path of the dispensing heads in their
forward and/or reverse movement. Once the dispensing heads return
to their starting point along the X direction, they may move to
another position along an indexing direction, referred to herein as
the Y direction, and continue to build the same layer by reciprocal
movement along the X direction. Alternately, the dispensing heads
may move in the Y direction between forward and reverse movements
or after more than one forward-reverse movement. The series of
scans performed by the dispensing heads to complete a single layer
is referred to herein as a single scan cycle.
Once the layer is completed, tray 360 is lowered in the Z direction
to a predetermined Z level, according to the desired thickness of
the layer subsequently to be printed. The procedure is repeated to
form three-dimensional object 112 in a layerwise manner.
In another embodiment, tray 360 may be displaced in the Z direction
between forward and reverse passages of the dispensing head of unit
116, within the layer. Such Z displacement is carried out in order
to cause contact of the leveling device with the surface in one
direction and prevent contact in the other direction.
System 110 optionally and preferably comprises a building material
supply system 330 which comprises the building material containers
or cartridges and supplies a plurality of building materials to
fabrication apparatus 114.
A control unit 340 controls fabrication apparatus 114 and
optionally and preferably also supply system 330. Control unit 340
typically includes an electronic circuit configured to perform the
controlling operations. Control unit 340 preferably communicates
with a data processor 154 which transmits digital data pertaining
to fabrication instructions based on computer object data, e.g., a
CAD configuration represented on a computer readable medium in a
form of, for example, a Standard Tessellation Language (STL) format
Standard Tessellation Language (STL), StereoLithography Contour
(SLC) format, Virtual Reality Modeling Language (VRML). Additive
Manufacturing File (AMF) format, Drawing Exchange Format (DXF),
Polygon File Format (PLY) or any other format suitable for CAD.
Typically, control unit 340 controls the voltage applied to each
printing head or nozzle array and the temperature of the building
material in the respective printing head.
Once the manufacturing data is loaded to control unit 340 it can
operate without user intervention. In some embodiments, control
unit 340 receives additional input from the operator, e.g., using
data processor 154 or using a user interface 118 communicating with
unit 340. User interface 118 can be of any type known in the art,
such as, but not limited to, a keyboard, a touch screen and the
like. For example, control unit 340 can receive, as additional
input, one or more building material types and/or attributes, such
as, but not limited to, color, characteristic distortion and/or
transition temperature, viscosity, electrical property, magnetic
property. Other attributes and groups of attributes are also
contemplated.
It is expected that during the life of a patent maturing from this
application many relevant components of a ROMP system as described
herein will be developed and the scope of the terms ROMP monomer,
ROMP inhibitor, ROMP activator, ROMP pre-catalyst, is intended to
include all such new technologies a priori.
As used herein the term "about" refers to +10% or .+-.5%.
The terms "comprises", "comprising", "includes", "including",
"having" and their conjugates mean "including but not limited
to".
The term "consisting of" means "including and limited to".
The term "consisting essentially of" means that the composition,
method or structure may include additional ingredients, steps
and/or parts, but only if the additional ingredients, steps and/or
parts do not materially alter the basic and novel characteristics
of the claimed composition, method or structure.
As used herein, the singular form "a", "an" and "the" include
plural references unless the context clearly dictates otherwise.
For example, the term "a compound" or "at least one compound" may
include a plurality of compounds, including mixtures thereof.
Throughout this application, various embodiments of this invention
may be presented in a range format. It should be understood that
the description in range format is merely for convenience and
brevity and should not be construed as an inflexible limitation on
the scope of the invention. Accordingly, the description of a range
should be considered to have specifically disclosed all the
possible subranges as well as individual numerical values within
that range. For example, description of a range such as from 1 to 6
should be considered to have specifically disclosed subranges such
as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6,
from 3 to 6 etc, as well as individual numbers within that range,
for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the
breadth of the range.
Whenever a numerical range is indicated herein, it is meant to
include any cited numeral (fractional or integral) within the
indicated range. The phrases "ranging/ranges between" a first
indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are
used herein interchangeably and are meant to include the first and
second indicated numbers and all the fractional and integral
numerals therebetween.
As used herein the term "method" refers to manners, means,
techniques and procedures for accomplishing a given task including,
but not limited to, those manners, means, techniques and procedures
either known to, or readily developed from known manners, means,
techniques and procedures by practitioners of the chemical,
pharmacological, biological, biochemical and medical arts.
Herein throughout, the phrase "linking moiety" or "linking group"
describes a group that connects two or more moieties or groups in a
compound. A linking moiety is typically derived from a bi- or
tri-functional compound, and can be regarded as a bi- or
tri-radical moiety, which is connected to two or three other
moieties, via two or three atoms thereof, respectively.
Exemplary linking moieties include a hydrocarbon moiety or chain,
optionally interrupted by one or more heteroatoms, as defined
herein, and/or any of the chemical groups listed below, when
defined as linking groups.
When a chemical group is referred to herein as "end group" it is to
be interpreted as a substituent, which is connected to another
group via one atom thereof.
Herein throughout, the term "hydrocarbon" collectively describes a
chemical group composed mainly of carbon and hydrogen atoms. A
hydrocarbon can be comprised of alkyl, alkene, alkyne, aryl, and/or
cycloalkyl, each can be substituted or unsubstituted, and can be
interrupted by one or more heteroatoms. The number of carbon atoms
can range from 2 to 20, and is preferably lower, e.g., from 1 to
10, or from 1 to 6, or from 1 to 4. A hydrocarbon can be a linking
group or an end group.
Bisphenol A is An example of a hydrocarbon comprised of 2 aryl
groups and one alkyl group.
As used herein, the term "amine" describes both a --NR'R'' group
and a --NR'-- group, wherein R' and R'' are each independently
hydrogen, alkyl, cycloalkyl, aryl, as these terms are defined
hereinbelow.
The amine group can therefore be a primary amine, where both R' and
R'' are hydrogen, a secondary amine, where R' is hydrogen and R''
is alkyl, cycloalkyl or aryl, or a tertiary amine, where each of R'
and R'' is independently alkyl, cycloalkyl or aryl.
Alternatively, R' and R'' can each independently be hydroxyalkyl,
trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl,
heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate,
hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy,
cyano, nitro, azo, sulfonamide, carbonyl, C-carboxylate,
O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,
N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and
hydrazine.
The term "amine" is used herein to describe a --NR'R'' group in
cases where the amine is an end group, as defined hereinunder, and
is used herein to describe a --NR'-- group in cases where the amine
is a linking group or is or part of a linking moiety.
The term "alkyl" describes a saturated aliphatic hydrocarbon
including straight chain and branched chain groups. Preferably, the
alkyl group has 1 to 20 carbon atoms. Whenever a numerical range;
e.g., "1-20", is stated herein, it implies that the group, in this
case the alkyl group, may contain 1 carbon atom, 2 carbon atoms, 3
carbon atoms, etc., up to and including 20 carbon atoms. More
preferably, the alkyl is a medium size alkyl having 1 to 10 carbon
atoms. Most preferably, unless otherwise indicated, the alkyl is a
lower alkyl having 1 to 4 carbon atoms (C(1-4) alkyl). The alkyl
group may be substituted or unsubstituted. Substituted alkyl may
have one or more substituents, whereby each substituent group can
independently be, for example, hydroxyalkyl, trihaloalkyl,
cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic,
amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy,
aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo,
sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate,
O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide,
N-amide, guanyl, guanidine and hydrazine.
The alkyl group can be an end group, as this phrase is defined
hereinabove, wherein it is attached to a single adjacent atom, or a
linking group, as this phrase is defined hereinabove, which
connects two or more moieties via at least two carbons in its
chain. When the alkyl is a linking group, it is also referred to
herein as "alkylene" or "alkylene chain".
Alkene (or alkenyl) and Alkyne (or alkynyl), as used herein, are an
alkyl, as defined herein, which contains one or more double bond or
triple bond, respectively.
The term "cycloalkyl" describes an all-carbon monocyclic ring or
fused rings (i.e., rings which share an adjacent pair of carbon
atoms) group where one or more of the rings does not have a
completely conjugated pi-electron system. Examples include, without
limitation, cyclohexane, adamantine, norbornyl, isobornyl, and the
like. The cycloalkyl group may be substituted or unsubstituted.
Substituted cycloalkyl may have one or more substituents, whereby
each substituent group can independently be, for example,
hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl,
heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide,
phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,
thioaryloxy, cyano, nitro, azo, sulfonamide. C-carboxylate,
O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,
N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and
hydrazine. The cycloalkyl group can be an end group, as this phrase
is defined hereinabove, wherein it is attached to a single adjacent
atom, or a linking group, as this phrase is defined hereinabove,
connecting two or more moieties at two or more positions
thereof.
The term "heteroalicyclic" describes a monocyclic or fused ring
group having in the ring(s) one or more atoms such as nitrogen,
oxygen and sulfur. The rings may also have one or more double
bonds. However, the rings do not have a completely conjugated
pi-electron system. Representative examples are piperidine,
piperazine, tetrahydrofuran, tetrahydropyrane, morpholine,
oxalidine, and the like. The heteroalicyclic may be substituted or
unsubstituted. Substituted heteroalicyclic may have one or more
substituents, whereby each substituent group can independently be,
for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl,
alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide,
sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy,
thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo,
sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate,
O-thiocarbamate, urea, thiourea, O-carbamate, N-carbamate, C-amide,
N-amide, guanyl, guanidine and hydrazine. The heteroalicyclic group
can be an end group, as this phrase is defined hereinabove, where
it is attached to a single adjacent atom, or a linking group, as
this phrase is defined hereinabove, connecting two or more moieties
at two or more positions thereof.
The term "aryl" describes an all-carbon monocyclic or fused-ring
polycyclic (i.e. rings which share adjacent pairs of carbon atoms)
groups having a completely conjugated pi-electron system. The aryl
group may be substituted or unsubstituted. Substituted aryl may
have one or more substituents, whereby each substituent group can
independently be, for example, hydroxyalkyl, trihaloalkyl,
cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic,
amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy,
aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo,
sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate,
O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide,
N-amide, guanyl, guanidine and hydrazine. The aryl group can be an
end group, as this term is defined hereinabove, wherein it is
attached to a single adjacent atom, or a linking group, as this
term is defined hereinabove, connecting two or more moieties at two
or more positions thereof.
The term "heteroaryl" describes a monocyclic or fused ring (i.e.,
rings which share an adjacent pair of atoms) group having in the
ring(s) one or more atoms, such as, for example, nitrogen, oxygen
and sulfur and, in addition, having a completely conjugated
pi-electron system. Examples, without limitation, of heteroaryl
groups include pyrrole, furan, thiophene, imidazole, oxazole,
thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline
and purine. The heteroaryl group may be substituted or
unsubstituted. Substituted heteroaryl may have one or more
substituents, whereby each substituent group can independently be,
for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl,
alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide,
sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy,
thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo,
sulfonamide, C-carboxylate, O-carboxylate. N-thiocarbamate,
O-thiocarbamate, urea, thiourea, O-carbamate, N-carbamate. C-amide.
N-amide, guanyl, guanidine and hydrazine. The heteroaryl group can
be an end group, as this phrase is defined hereinabove, where it is
attached to a single adjacent atom, or a linking group, as this
phrase is defined hereinabove, connecting two or more moieties at
two or more positions thereof. Representative examples are
pyridine, pyrrole, oxazole, indole, purine and the like.
The term "halide", "halogen" and "halo" describe fluorine,
chlorine, bromine or iodine.
The term "haloalkyl" describes an alkyl group as defined above,
further substituted by one or more halide.
The term "sulfate" describes a --O--S(.dbd.O).sub.2--OR' end group,
as this term is defined hereinabove, or an
--O--S(.dbd.O).sub.2--O-- linking group, as these phrases are
defined hereinabove, where R' is as defined hereinabove.
The term "thiosulfate" describes a --O--S(.dbd.S)(.dbd.O)--OR' end
group or a --O--S(.dbd.S).dbd.O)--O-- linking group, as these
phrases are defined hereinabove, where R' is as defined
hereinabove.
The term "sulfite" describes an --O--S(.dbd.O)--O--R' end group or
a --O--S(.dbd.--O)--O-- group linking group, as these phrases are
defined hereinabove, where R' is as defined hereinabove.
The term "thiosulfite" describes a --O--S(.dbd.S)--O--R' end group
or an --O--S(.dbd.S)--O-- group linking group, as these phrases are
defined hereinabove, where R' is as defined hereinabove.
The term "sulfinate" describes a --S(.dbd.O)--OR' end group or an
--S(.dbd.O)--O-- group linking group, as these phrases are defined
hereinabove, where R' is as defined hereinabove.
The term "sulfoxide" or "sulfinyl" describes a --S(.dbd.O)R' end
group or an --S(.dbd.O)-- linking group, as these phrases are
defined hereinabove, where R' is as defined hereinabove.
The term "sulfonate" describes a --S(.dbd.O).sub.2--R' end group or
an --S(.dbd.O).sub.2-- linking group, as these phrases are defined
hereinabove, where R' is as defined herein.
The term "S-sulfonamide" describes a --S(.dbd.O).sub.2--NR'R'' end
group or a --S(.dbd.O).sub.2--NR'-- linking group, as these phrases
are defined hereinabove, with R' and R'' as defined herein.
The term "N-sulfonamide" describes an R'S(.dbd.O).sub.2--NR''-- end
group or a --S(.dbd.O).sub.2--NR'-- linking group, as these phrases
are defined hereinabove, where R' and R'' are as defined
herein.
The term "disulfide" refers to a --S--SR' end group or a --S--S--
linking group, as these phrases are defined hereinabove, where R'
is as defined herein.
The term "oxo" as used herein, describes a (.dbd.O) group, wherein
an oxygen atom is linked by a double bond to the atom (e.g., carbon
atom) at the indicated position.
The term "thiooxo" as used herein, describes a (.dbd.S) group,
wherein a sulfur atom is linked by a double bond to the atom (e.g.,
carbon atom) at the indicated position.
The term "oxime" describes a .dbd.N--OH end group or a .dbd.N--O--
linking group, as these phrases are defined hereinabove.
The term "hydroxyl" describes a --OH group.
The term "alkoxy" describes both an --O-alkyl and an --O-cycloalkyl
group, as defined herein.
The term "aryloxy" describes both an --O-aryl and an --O-heteroaryl
group, as defined herein.
The term "thiohydroxy" describes a --SH group.
The term "thioalkoxy" describes both a --S-alkyl group, and a
--S-cycloalkyl group, as defined herein.
The term "thioaryloxy" describes both a --S-aryl and a
--S-heteroaryl group, as defined herein.
The "hydroxyalkyl" is also referred to herein as "alcohol", and
describes an alkyl, as defined herein, substituted by a hydroxy
group.
The term "cyano" describes a --C.ident.N group.
The term "cyanurate" describes a
##STR00047## end group or
##STR00048## linking group, with R' and R'' as defined herein.
The term "isocyanurate" describes a
##STR00049## end group or
##STR00050## linking group, with R' and R'' as defined herein.
The term "thiocyanurate" describes a
##STR00051## end group or
##STR00052## linking group, with R' and R'' as defined herein.
The term "isocyanate" describes an --N.dbd.C.dbd.O group.
The term "isothiocyanate" describes an --N.dbd.C.dbd.S group.
The term "nitro" describes an --NO.sub.2 group.
The term "acyl halide" describes a --(C.dbd.O)R'''' group wherein
R'''' is halide, as defined hereinabove.
The term "azo" or "diazo" describes an --N.dbd.NR' end group or an
--N.dbd.N-- linking group, as these phrases are defined
hereinabove, with R' as defined hereinabove.
The term "peroxo" describes an --O--OR' end group or an --O--O--
linking group, as these phrases are defined hereinabove, with R' as
defined hereinabove.
The term "carboxylate" as used herein encompasses C-carboxylate and
O-carboxylate.
The term "C-carboxylate" describes a --C(.dbd.O)--OR' end group or
a --C(.dbd.O)--O-- linking group, as these phrases are defined
hereinabove, where R' is as defined herein.
The term "O-carboxylate" describes a --OC(.dbd.O)R' end group or a
--OC(.dbd.O)-- linking group, as these phrases are defined
hereinabove, where R' is as defined herein.
A carboxylate can be linear or cyclic. When cyclic. R' and the
carbon atom are linked together to form a ring, in C-carboxylate,
and this group is also referred to as lactone. Alternatively. R'
and O are linked together to form a ring in O-carboxylate. Cyclic
carboxylates can function as a linking group, for example, when an
atom in the formed ring is linked to another group.
The term "thiocarboxylate" as used herein encompasses
C-thiocarboxylate and O-thiocarboxylate.
The term "C-thiocarboxylate" describes a --C(.dbd.S)--OR' end group
or a --C(.dbd.S)--O-- linking group, as these phrases are defined
hereinabove, where R' is as defined herein.
The term "O-thiocarboxylate" describes a --OC(.dbd.S)R' end group
or a --OC(.dbd.S)-- linking group, as these phrases are defined
hereinabove, where R' is as defined herein.
A thiocarboxylate can be linear or cyclic. When cyclic. R' and the
carbon atom are linked together to form a ring, in
C-thiocarboxylate, and this group is also referred to as
thiolactone. Alternatively, R' and O are linked together to form a
ring in O-thiocarboxylate. Cyclic thiocarboxylates can function as
a linking group, for example, when an atom in the formed ring is
linked to another group.
The term "carbamate" as used herein encompasses N-carbamate and
O-carbamate.
The term "N-carbamate" describes an R''OC(.dbd.O)--NR'-- end group
or a --OC(.dbd.O)--NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "O-carbamate" describes an --OC(.dbd.O)--NR'R'' end group
or an --OC(.dbd.O)--NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
A carbamate can be linear or cyclic. When cyclic. R' and the carbon
atom are linked together to form a ring, in O-carbamate.
Alternatively, R' and O are linked together to form a ring in
N-carbamate. Cyclic carbamates can function as a linking group, for
example, when an atom in the formed ring is linked to another
group.
The term "carbamate" as used herein encompasses N-carbamate and
O-carbamate.
The term "thiocarbamate" as used herein encompasses N-thiocarbamate
and O-thiocarbamate.
The term "O-thiocarbamate" describes a --OC(.dbd.S)--NR'R'' end
group or a --OC(.dbd.S)--NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "N-thiocarbamate" describes an R''OC(.dbd.S)NR'-- end
group or a --OC(.dbd.S)NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
Thiocarbamates can be linear or cyclic, as described herein for
carbamates.
The term "dithiocarbamate" as used herein encompasses
S-dithiocarbamate and N-dithiocarbamate.
The term "S-dithiocarbamate" describes a --SC(.dbd.S)--NR'R'' end
group or a --SC(.dbd.S)NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "N-dithiocarbamate" describes an R''SC(.dbd.S)NR'-- end
group or a --SC(.dbd.S)NR'-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "urea", which is also referred to herein as "ureido",
describes a --NR'C(.dbd.O)--NR''R''' end group or a
--NR'C(.dbd.O)--NR''-- linking group, as these phrases are defined
hereinabove, where R' and R'' are as defined herein and R''' is as
defined herein for R' and R''.
The term "thiourea", which is also referred to herein as
"thioureido", describes a --NR'--C(.dbd.S)--NR''R''' end group or a
--NR'--C(.dbd.S)--NR''-- linking group, with R', R'' and R''' as
defined herein.
The term "amide" as used herein encompasses C-amide and
N-amide.
The term "C-amide" describes a --C(.dbd.O)--NR'R'' end group or a
--C(.dbd.O)--NR'-linking group, as these phrases are defined
hereinabove, where R' and R'' are as defined herein.
The term "N-amide" describes a R'C(.dbd.O)--NR''-- end group or a
R'C(.dbd.O)--N-- linking group, as these phrases are defined
hereinabove, where R' and R'' are as defined herein.
An amide can be linear or cyclic. When cyclic, R' and the carbon
atom are linked together to form a ring, in C-amide, and this group
is also referred to as lactam.
Cyclic amides can function as a linking group, for example, when an
atom in the formed ring is linked to another group.
The term "guanyl" describes a R'R''NC(.dbd.N)-- end group or a
--R'NC(.dbd.N)-- linking group, as these phrases are defined
hereinabove, where R' and R'' are as defined herein.
The term "guanidine" describes a --R'NC(.dbd.N)--NR''R''' end group
or a --R'NC(.dbd.N)--NR''-- linking group, as these phrases are
defined hereinabove, where R', R'' and R''' are as defined
herein.
The term "hydrazine" describes a --NR'--NR''R''' end group or a
--NR'--NR''-linking group, as these phrases are defined
hereinabove, with R', R'', and R''' as defined herein.
As used herein, the term "hydrazide" describes a
--C(.dbd.O)--NR'--NR''R''' end group or a --C(.dbd.O)--NR'--NR''--
linking group, as these phrases are defined hereinabove, where R',
R'' and R''' are as defined herein.
As used herein, the term "thiohydrazide" describes a
--C(.dbd.S)--NR'--NR''R''' end group or a --C(.dbd.S)--NR'--NR''--
linking group, as these phrases are defined hereinabove, where R',
R'' and R''' are as defined herein.
As used herein, the term "alkylene glycol" describes a
--O--[(CR'R'').sub.z--O].sub.y--R''' end group or a
--O--[(CR'R'').sub.x--O].sub.y-- linking group, with R', R'' and
R''' being as defined herein, and with z being an integer of from 1
to 10, preferably, 2-6, more preferably 2 or 3, and y being an
integer of 1 or more. Preferably R' and R'' are both hydrogen. When
z is 2 and y is 1, this group is ethylene glycol. When z is 3 and y
is 1, this group is propylene glycol.
When y is greater than 4, the alkylene glycol is referred to herein
as poly(alkylene glycol). In some embodiments of the present
invention, a poly(alkylene glycol) group or moiety can have from 10
to 200 repeating alkylene glycol units, such that z is 10 to 200,
preferably 10-100, more preferably 10-50.
The term "silyl" describes a --SiR'R''R''' end group or a
--SiR'R''-- linking group, as these phrases are defined
hereinabove, whereby each of R', R'' and R''' are as defined
herein.
The term "siloxy" describes a --Si(OR')R''R''' end group or a
--Si(OR')R''-linking group, as these phrases are defined
hereinabove, whereby each of R', R'' and R''' are as defined
herein.
The term "silaza" describes a --Si(NR'R'')R''' end group or a
--Si(NR'R'')-- linking group, as these phrases are defined
hereinabove, whereby each of R', R'' and R''' is as defined
herein.
The term "silicate" describes a --O--Si(OR')(OR'')(OR''') end group
or a --O--Si(OR')(OR'')-- linking group, as these phrases are
defined hereinabove, with R', R'' and R''' as defined herein.
The term "boryl" describes a --BR'R'' end group or a --BR'--
linking group, as these phrases are defined hereinabove, with R'
and R'' are as defined herein.
The term "borate" describes a --O--B(OR')(OR'') end group or a
--O--B(OR')(O--) linking group, as these phrases are defined
hereinabove, with R' and R'' are as defined herein.
As used herein, the term "epoxide" describes a
##STR00053## end group or a
##STR00054## linking group, as these phrases are defined
hereinabove, where R', R'' and R''' are as defined herein.
As used herein, the term "methyleneamine" describes an
--NR'--CH.sub.2--CH.dbd.CR''R''' end group or a
--NR'--CH.sub.2--CH.dbd.CR''-- linking group, as these phrases are
defined hereinabove, where R', R'' and R''' are as defined
herein.
The term "phosphonate" describes a --P(.dbd.O)(OR')(OR'') end group
or a --P(.dbd.O)(OR')(O)-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "thiophosphonate" describes a --P(.dbd.S)(OR')(OR'') end
group or a --P(.dbd.S)(OR')(O)-- linking group, as these phrases
are defined hereinabove, with R' and R'' as defined herein.
The term "phosphinyl" describes a --PR'R'' end group or a --PR'--
linking group, as these phrases are defined hereinabove, with R'
and R'' as defined hereinabove.
The term "phosphine oxide" describes a --P(.dbd.O)(R')(R'') end
group or a --P(.dbd.O)(R')-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "phosphine sulfide" describes a --P(.dbd.S)(R')(R'') end
group or a --P(.dbd.S)(R')-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "phosphite" describes an --O--PR'(.dbd.O)(OR'') end group
or an --O-PH(.dbd.O)(O)-- linking group, as these phrases are
defined hereinabove, with R' and R'' as defined herein.
The term "carbonyl" or "carbonate" as used herein, describes a
--C(.dbd.O)--R' end group or a --C(.dbd.O)-- linking group, as
these phrases are defined hereinabove, with R' as defined herein.
This term encompasses ketones and aldehydes.
The term "thiocarbonyl" as used herein, describes a --C(.dbd.S)--R'
end group or a --C(.dbd.S)-- linking group, as these phrases are
defined hereinabove, with R' as defined herein.
The term "oxime" describes a .dbd.N--OH end group or a .dbd.N--O--
linking group, as these phrases are defined hereinabove.
The term "cyclic ring" encompasses a cycloalkyl, a
heretroalicyclic, an aryl (an aromatic ring) and a heteroaryl (a
heteroaromatic ring).
Other chemical groups are to be regarded according to the common
definition thereof in the art and/or in line of the definitions
provided herein.
It is appreciated that certain features of the invention, which
are, for clarity, described in the context of separate embodiments,
may also be provided in combination in a single embodiment.
Conversely, various features of the invention, which are, for
brevity, described in the context of a single embodiment, may also
be provided separately or in any suitable subcombination or as
suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
Various embodiments and aspects of the present invention as
delineated hereinabove and as claimed in the claims section below
find experimental support in the following examples.
EXAMPLES
Reference is now made to the following examples, which together
with the above descriptions illustrate some embodiments of the
invention in a non limiting fashion.
EXPERIMENTAL METHODS
Thermo-mechanical properties of the polymerized material were
determined by measuring the elongation, impact strength and HDT
according to respective ASTM procedures, as follows:
The impact strength of polymerized (cured) materials was measured
by a Resil 5.5 J type instrument (CEAST Series, Instron.RTM. (USA))
using an Izod impact test (notched Izod) according to the ASTM
International organization D-256 standard.
The Heat deflection temperature (HDT) of the samples was determined
according to the ASTM International organization D-648 standard
using a HDT 3 VICAT instrument (CEAST Series, Instron.RTM.
(USA)).
The elongation (%) of polymerized materials was measured using
Lloyd LR 5k instruments (Lloyd Instruments, UK according to the
ASTM International organization D-638-05 standard.
Example 1
Modeling Material Formulation System
The present inventors have uncovered that using a "dual jetting
single curing" approach in 3D inkjet printing of ROMP systems
provides objects with exceptional properties. In the most suitable
formulation system, a catalyst system which comprises a
pre-catalyst and an acid generator as an activator or co-catalyst
is used as follows: a first formulation (Part A) comprises ROMP
monomer or monomers, a pre-catalyst and a ROMP inhibitor, and is
also denoted as "pre-catalyst component" and a second formulation
(Part B) comprises ROMP monomer or monomers, and an activator (an
acid generator), and is also denoted as "activator component". In
some embodiments, impact modifying agent (e.g., an elastomer) is
added to one or both of the formulations.
An exemplary formulation system utilized while practicing this
methodology is presented in Table 1.
TABLE-US-00005 TABLE 1 Catalyst component (Part A) Activator
component (Part B) Concentration Concentration Component (w/w)
Component (w/w) RIM 90-92% RIM 90-92% monomer monomer Toughening
1-10% Toughening 1-10% agent agent ROMP 0.01-0.02% Activator
0.05-2% inhibitor (10-20 ppm) (e.g., (e.g., P(OEt).sub.3)
PhSiCl.sub.3) Ru-based 0.01-0.1% pre-catalyst (e.g., VC 1161;
VC843):
Using this formulation in a 3D inkjet printing method, using Objet
Connex.TM. (Stratasys Ltd., Israel) system, such as described
herein, and post-curing the obtained object for 2 hours at
150.degree. C., resulted in an object featuring the following
properties:
HDT=130-140.degree. C. (e.g., 138.degree. C.)
Impact=150-350 J/m (e.g., 260 J/m)
Elongation=about 25%.
Example 2
Reactivity Assays
Reactivity assays of a formulation system as described in Example 1
above were performed as follows:
One drop (25 .mu.L) of part A (catalyst component) was placed on a
temperature-controlled aluminum surface. A drop (25 .mu.L) of part
B (activator component) was placed on the first drop. Time to cure
was determined as thin film was formed. Reactivity was measured as
the time required for a white color to appear after a drop of Part
B was placed onto the drop of Part A.
Unless otherwise indicated, all experiments were performed using a
RIM monomer (as exemplary ROMP monomers), 8% CP1100 (as an
exemplary impact modifying agent), and 0.08% PhSiCl.sub.3 (as an
exemplary activator), at a temperature of 26.degree. C.
Reactivity Studies Using Various Combinations of Pre-Catalysts:
Two exemplary Ru-based pre-catalysts were studied: VC1161 and VC843
(see. Table B). VC843 has better stability toward decomposition
than VC1161. VC 1161 is more reactive than VC843 following
activation. Theoretically. VC1161 allows immediate solidification
of the deposited layer and VC843 is much slower but allows high
conversion degree of the polymer.
P(OEt).sub.3 was used as an exemplary ROMP inhibitor is all tested
formulations, at the indicated concentration.
Table 2 below presents the data obtained in these studies.
TABLE-US-00006 TABLE 2 VC 1161 VC843 P(OEt).sub.3 Time to cure # (%
wt.) (% wt.) % VC 1161 (ppm) (second) 1 0.0196% 0.0294% 40% VC1161
15 24 .+-. 4 2 0.044% 0.0111% 80% VC1161 15 16 .+-. 1 3 0.031%
0.0208% 60% VC1161 15 20 .+-. 1 4 0.0584% -- 100% VC1161 15 12 .+-.
1 5 0.0584% -- 100% VC1161 2 8 .+-. 1
Due to the higher conversion obtained by VC 843 and the higher
reactivity of VC1161, a formulation comprising 40% VC1161 was
determined as an exemplary preferred formulation.
Effect of ROMP Inhibitor Concentration:
In all the assays conducted for evaluating the effect of the
concentration of a ROMP inhibitor, P(OEt).sub.3 was used as an
exemplary ROMP inhibitor; Chlorodimethylphenyl Silane was used as
an activator, at a concentration of 0.387 wt. %; and VC 1161 was
used as a pre-catalyst, at a concentration of 0.0425% by weight
(+1% BHT as an exemplary antioxidant).
The obtained data is presented in Table 3 below.
TABLE-US-00007 TABLE 3 P(OEt).sub.3 Time (ppm) to Cure 0 26 sec 2
33 sec 5 38 sec 15 50 sec
Effect of Temperature:
The following formulation system was used in these assays:
TABLE-US-00008 Compound Weight % Part A 10% P(OEt).sub.3 0.015 60%
VC834:40% VC1161 0.049 Butanol 1 8% CP1100 in RIM 99 monomer Part B
PhSiMe.sub.2Cl 0.5 8% CP1100 in RIM 99.5 monomer
The obtained data is presented in Table 4 below.
TABLE-US-00009 TABLE 4 Temperature Curing time (.degree. C.)
(Seconds) 25 16.5 35 14.5 40 14 50 8
Higher temperatures are inapplicable due to volatility and
flammability of ROMP monomers. A temperature of 50.degree. C.
provides satisfactory reactivity.
Effect of Pentafluoropropionic Acid Concentration:
The effect of pentafluoropropionic acid as an activator, at various
concentrations, was evaluated, while using as a pre-catalyst a
40:60 VC1161:VC843 mixture. The obtained data is presented in Table
5 below.
TABLE-US-00010 TABLE 5 Concentration of Time activator (Wt. %) to
Cure HDT 0.2 1 min 5 sec 54.3 0.6 25 sec 60.2 1.8 13 sec 70.4
Effect of Activator Type:
In this set of experiments. Part A formulations containing 20 grams
of RIM monomer with 8% CP1100 and 0.012 gram of VC1161 as a
pre-catalyst was used. The Part B formulation contained 1.99 grams
RIM monomer with 8% CP1100, and 0.01 gram (0.5% by weight) of an
activator. The obtained data is presented in Table 6 below.
TABLE-US-00011 TABLE 6 Time to Cure Activator chemical name
Activator structure (Sec) ChloroDimethyl Phenyl Silane, M.sub.w =
170.71 g/mol ##STR00055## 92, 75, 83 ChloroTrimethylSilane, M.sub.w
= 108.64 g/mol ##STR00056## 36, 36, 37 Butyl(chloro)dimethyl
Silane, M.sub.w = 150.72 g/mol ##STR00057## 66, 63, 64
Chloro-decyl-dimethyl Silane, M.sub.w = 234.88 g/mol ##STR00058##
120, 100 Chloro(chloromethyl)dimethyl Silane, M.sub.w = 143.09
g/mol ##STR00059## 20, 23, 22 Trichloro(phenyl)silane, M.sub.w =
211.55 g/mol ##STR00060## 16, 13, 11 Trichlorododecyl silane (TCSA)
M.sub.w = 303.77 g/mol ##STR00061## 22, 23, 21 Trichloro(octadecyl)
silane CH.sub.3(CH.sub.2).sub.16CH.sub.2SiCl.sub.3 25, 25, 26
M.sub.w = 387.93 g/mol Dichlorodiphenyl silane M.sub.w = 253.20
g/mol ##STR00062## 110, 113, 111 Perfluoro decyldimethylchloro
silane M.sub.w = 540.73 g/mol ##STR00063## Gelation only Perfluoro
decylmethyl dichlorosilane 561.14 g/mol ##STR00064## Gelation
only
Trichloro(phenyl)silane was shown to be the most efficient
activator. This activator, however, is sensitive to moisture and
requires operating the printing system under inert atmosphere.
Chlorodimethylphenyl Silane is less efficient as activator, but
allows continuous jetting under air conditions.
Chloro(dichloromethyl) methyl silane (DDS) was shown as a moderate
activator but allows performing the printing process without
affecting the printing heads. This material, however, is
volatile.
Effect of Activator Concentration:
The effect of various concentrations of Chlorodimethylphenyl Silane
as an activator in the Part B formulation was tested while using a
Part A formulation comprising 0.0586% by weight of VC1161 (26300/1
monomer/pre-catalyst ratio). The results are presented in Table 7
below.
TABLE-US-00012 TABLE 7 Activator Time to cure activator w/w % (Sec)
##STR00065## 0.129 25 ##STR00066## 0.387 17 ##STR00067## 0.50
13
Although the invention has been described in conjunction with
specific embodiments thereof, it is evident that many alternatives,
modifications and variations will be apparent to those skilled in
the art. Accordingly, it is intended to embrace all such
alternatives, modifications and variations that fall within the
spirit and broad scope of the appended claims.
All publications, patents and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention. To the extent that section headings are used,
they should not be construed as necessarily limiting.
* * * * *